.github/workflows/codecov.yml

@@ -36,7 +36,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        go: ['1.19', '1.20', '1.23']
+        go: ['1.20', '1.21', '1.22', '1.23']
     steps:
     - name: Harden Runner
       uses: step-security/harden-runner@91182cccc01eb5e619899d80e4e971d6181294a7 # v2.10.1

.github/workflows/codeql-analysis.yml

@@ -54,7 +54,7 @@ jobs:
 
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL
-      uses: github/codeql-action/init@294a9d92911152fe08befb9ec03e240add280cb3 # v3.26.8
+      uses: github/codeql-action/init@4dd16135b69a43b6c8efb853346f8437d92d3c93 # v3.26.6
       with:
         languages: ${{ matrix.language }}
         # If you wish to specify custom queries, you can do so here or in a config file.
@@ -65,7 +65,7 @@ jobs:
     # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
     # If this step fails, then you should remove it and run the build manually (see below)
     - name: Autobuild
-      uses: github/codeql-action/autobuild@294a9d92911152fe08befb9ec03e240add280cb3 # v3.26.8
+      uses: github/codeql-action/autobuild@4dd16135b69a43b6c8efb853346f8437d92d3c93 # v3.26.6
 
     # ℹ️ Command-line programs to run using the OS shell.
     # 📚 https://git.io/JvXDl
@@ -79,4 +79,4 @@ jobs:
     #   make release
 
     - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@294a9d92911152fe08befb9ec03e240add280cb3 # v3.26.8
+      uses: github/codeql-action/analyze@4dd16135b69a43b6c8efb853346f8437d92d3c93 # v3.26.6

.github/workflows/scorecards.yml

@@ -75,6 +75,6 @@ jobs:
 
       # Upload the results to GitHub's code scanning dashboard.
       - name: "Upload to code-scanning"
-        uses: github/codeql-action/upload-sarif@294a9d92911152fe08befb9ec03e240add280cb3 # v3.26.8
+        uses: github/codeql-action/upload-sarif@4dd16135b69a43b6c8efb853346f8437d92d3c93 # v3.26.6
         with:
           sarif_file: results.sarif

client.go

@@ -787,100 +787,3 @@ func (c *Client) auth() error {
 	}
 	return nil
 }
-
-// sendSingleMsg sends out a single message and returns an error if the transmission/delivery fails.
-// It is invoked by the public Send methods
-func (c *Client) sendSingleMsg(message *Msg) error {
-	if message.encoding == NoEncoding {
-		if ok, _ := c.smtpClient.Extension("8BITMIME"); !ok {
-			return &SendError{Reason: ErrNoUnencoded, isTemp: false, affectedMsg: message}
-		}
-	}
-	from, err := message.GetSender(false)
-	if err != nil {
-		return &SendError{
-			Reason: ErrGetSender, errlist: []error{err}, isTemp: isTempError(err),
-			affectedMsg: message,
-		}
-	}
-	rcpts, err := message.GetRecipients()
-	if err != nil {
-		return &SendError{
-			Reason: ErrGetRcpts, errlist: []error{err}, isTemp: isTempError(err),
-			affectedMsg: message,
-		}
-	}
-
-	if c.dsn {
-		if c.dsnmrtype != "" {
-			c.smtpClient.SetDSNMailReturnOption(string(c.dsnmrtype))
-		}
-	}
-	if err = c.smtpClient.Mail(from); err != nil {
-		retError := &SendError{
-			Reason: ErrSMTPMailFrom, errlist: []error{err}, isTemp: isTempError(err),
-			affectedMsg: message,
-		}
-		if resetSendErr := c.smtpClient.Reset(); resetSendErr != nil {
-			retError.errlist = append(retError.errlist, resetSendErr)
-		}
-		return retError
-	}
-	hasError := false
-	rcptSendErr := &SendError{affectedMsg: message}
-	rcptSendErr.errlist = make([]error, 0)
-	rcptSendErr.rcpt = make([]string, 0)
-	rcptNotifyOpt := strings.Join(c.dsnrntype, ",")
-	c.smtpClient.SetDSNRcptNotifyOption(rcptNotifyOpt)
-	for _, rcpt := range rcpts {
-		if err = c.smtpClient.Rcpt(rcpt); err != nil {
-			rcptSendErr.Reason = ErrSMTPRcptTo
-			rcptSendErr.errlist = append(rcptSendErr.errlist, err)
-			rcptSendErr.rcpt = append(rcptSendErr.rcpt, rcpt)
-			rcptSendErr.isTemp = isTempError(err)
-			hasError = true
-		}
-	}
-	if hasError {
-		if resetSendErr := c.smtpClient.Reset(); resetSendErr != nil {
-			rcptSendErr.errlist = append(rcptSendErr.errlist, resetSendErr)
-		}
-		return rcptSendErr
-	}
-	writer, err := c.smtpClient.Data()
-	if err != nil {
-		return &SendError{
-			Reason: ErrSMTPData, errlist: []error{err}, isTemp: isTempError(err),
-			affectedMsg: message,
-		}
-	}
-	_, err = message.WriteTo(writer)
-	if err != nil {
-		return &SendError{
-			Reason: ErrWriteContent, errlist: []error{err}, isTemp: isTempError(err),
-			affectedMsg: message,
-		}
-	}
-	message.isDelivered = true
-
-	if err = writer.Close(); err != nil {
-		return &SendError{
-			Reason: ErrSMTPDataClose, errlist: []error{err}, isTemp: isTempError(err),
-			affectedMsg: message,
-		}
-	}
-
-	if err = c.Reset(); err != nil {
-		return &SendError{
-			Reason: ErrSMTPReset, errlist: []error{err}, isTemp: isTempError(err),
-			affectedMsg: message,
-		}
-	}
-	if err = c.checkConn(); err != nil {
-		return &SendError{
-			Reason: ErrConnCheck, errlist: []error{err}, isTemp: isTempError(err),
-			affectedMsg: message,
-		}
-	}
-	return nil
-}

client_119.go

@@ -7,23 +7,111 @@
 
 package mail
 
-import "errors"
+import "strings"
 
 // Send sends out the mail message
 func (c *Client) Send(messages ...*Msg) error {
-	if err := c.checkConn(); err != nil {
+	if cerr := c.checkConn(); cerr != nil {
-		return &SendError{Reason: ErrConnCheck, errlist: []error{err}, isTemp: isTempError(err)}
+		return &SendError{Reason: ErrConnCheck, errlist: []error{cerr}, isTemp: isTempError(cerr)}
 	}
 	var errs []*SendError
-	for id, message := range messages {
+	for _, message := range messages {
-		if sendErr := c.sendSingleMsg(message); sendErr != nil {
+		message.sendError = nil
-			messages[id].sendError = sendErr
+		if message.encoding == NoEncoding {
-
+			if ok, _ := c.smtpClient.Extension("8BITMIME"); !ok {
-			var msgSendErr *SendError
+				sendErr := &SendError{Reason: ErrNoUnencoded, isTemp: false}
-			if errors.As(sendErr, &msgSendErr) {
+				message.sendError = sendErr
-				errs = append(errs, msgSendErr)
+				errs = append(errs, sendErr)
+				continue
 			}
 		}
+		from, err := message.GetSender(false)
+		if err != nil {
+			sendErr := &SendError{Reason: ErrGetSender, errlist: []error{err}, isTemp: isTempError(err)}
+			message.sendError = sendErr
+			errs = append(errs, sendErr)
+			continue
+		}
+		rcpts, err := message.GetRecipients()
+		if err != nil {
+			sendErr := &SendError{Reason: ErrGetRcpts, errlist: []error{err}, isTemp: isTempError(err)}
+			message.sendError = sendErr
+			errs = append(errs, sendErr)
+			continue
+		}
+
+		if c.dsn {
+			if c.dsnmrtype != "" {
+				c.smtpClient.SetDSNMailReturnOption(string(c.dsnmrtype))
+			}
+		}
+		if err = c.smtpClient.Mail(from); err != nil {
+			sendErr := &SendError{Reason: ErrSMTPMailFrom, errlist: []error{err}, isTemp: isTempError(err)}
+			if resetSendErr := c.smtpClient.Reset(); resetSendErr != nil {
+				sendErr.errlist = append(sendErr.errlist, resetSendErr)
+			}
+			message.sendError = sendErr
+			errs = append(errs, sendErr)
+			continue
+		}
+		failed := false
+		rcptSendErr := &SendError{}
+		rcptSendErr.errlist = make([]error, 0)
+		rcptSendErr.rcpt = make([]string, 0)
+		rcptNotifyOpt := strings.Join(c.dsnrntype, ",")
+		c.smtpClient.SetDSNRcptNotifyOption(rcptNotifyOpt)
+		for _, rcpt := range rcpts {
+			if err = c.smtpClient.Rcpt(rcpt); err != nil {
+				rcptSendErr.Reason = ErrSMTPRcptTo
+				rcptSendErr.errlist = append(rcptSendErr.errlist, err)
+				rcptSendErr.rcpt = append(rcptSendErr.rcpt, rcpt)
+				rcptSendErr.isTemp = isTempError(err)
+				failed = true
+			}
+		}
+		if failed {
+			if resetSendErr := c.smtpClient.Reset(); resetSendErr != nil {
+				rcptSendErr.errlist = append(rcptSendErr.errlist, err)
+			}
+			message.sendError = rcptSendErr
+			errs = append(errs, rcptSendErr)
+			continue
+		}
+		writer, err := c.smtpClient.Data()
+		if err != nil {
+			sendErr := &SendError{Reason: ErrSMTPData, errlist: []error{err}, isTemp: isTempError(err)}
+			message.sendError = sendErr
+			errs = append(errs, sendErr)
+			continue
+		}
+		_, err = message.WriteTo(writer)
+		if err != nil {
+			sendErr := &SendError{Reason: ErrWriteContent, errlist: []error{err}, isTemp: isTempError(err)}
+			message.sendError = sendErr
+			errs = append(errs, sendErr)
+			continue
+		}
+		message.isDelivered = true
+
+		if err = writer.Close(); err != nil {
+			sendErr := &SendError{Reason: ErrSMTPDataClose, errlist: []error{err}, isTemp: isTempError(err)}
+			message.sendError = sendErr
+			errs = append(errs, sendErr)
+			continue
+		}
+
+		if err = c.Reset(); err != nil {
+			sendErr := &SendError{Reason: ErrSMTPReset, errlist: []error{err}, isTemp: isTempError(err)}
+			message.sendError = sendErr
+			errs = append(errs, sendErr)
+			continue
+		}
+		if err = c.checkConn(); err != nil {
+			sendErr := &SendError{Reason: ErrConnCheck, errlist: []error{err}, isTemp: isTempError(err)}
+			message.sendError = sendErr
+			errs = append(errs, sendErr)
+			continue
+		}
 	}
 
 	if len(errs) > 0 {

client_120.go

@@ -9,6 +9,7 @@ package mail
 
 import (
 	"errors"
+	"strings"
 )
 
 // Send sends out the mail message
@@ -17,16 +18,92 @@ func (c *Client) Send(messages ...*Msg) (returnErr error) {
 		returnErr = &SendError{Reason: ErrConnCheck, errlist: []error{err}, isTemp: isTempError(err)}
 		return
 	}
+	for _, message := range messages {
+		message.sendError = nil
+		if message.encoding == NoEncoding {
+			if ok, _ := c.smtpClient.Extension("8BITMIME"); !ok {
+				message.sendError = &SendError{Reason: ErrNoUnencoded, isTemp: false}
+				returnErr = errors.Join(returnErr, message.sendError)
+				continue
+			}
+		}
+		from, err := message.GetSender(false)
+		if err != nil {
+			message.sendError = &SendError{Reason: ErrGetSender, errlist: []error{err}, isTemp: isTempError(err)}
+			returnErr = errors.Join(returnErr, message.sendError)
+			continue
+		}
+		rcpts, err := message.GetRecipients()
+		if err != nil {
+			message.sendError = &SendError{Reason: ErrGetRcpts, errlist: []error{err}, isTemp: isTempError(err)}
+			returnErr = errors.Join(returnErr, message.sendError)
+			continue
+		}
 
-	var errs []error
+		if c.dsn {
-	defer func() {
+			if c.dsnmrtype != "" {
-		returnErr = errors.Join(errs...)
+				c.smtpClient.SetDSNMailReturnOption(string(c.dsnmrtype))
-	}()
+			}
+		}
+		if err = c.smtpClient.Mail(from); err != nil {
+			message.sendError = &SendError{Reason: ErrSMTPMailFrom, errlist: []error{err}, isTemp: isTempError(err)}
+			returnErr = errors.Join(returnErr, message.sendError)
+			if resetSendErr := c.smtpClient.Reset(); resetSendErr != nil {
+				returnErr = errors.Join(returnErr, resetSendErr)
+			}
+			continue
+		}
+		failed := false
+		rcptSendErr := &SendError{}
+		rcptSendErr.errlist = make([]error, 0)
+		rcptSendErr.rcpt = make([]string, 0)
+		rcptNotifyOpt := strings.Join(c.dsnrntype, ",")
+		c.smtpClient.SetDSNRcptNotifyOption(rcptNotifyOpt)
+		for _, rcpt := range rcpts {
+			if err = c.smtpClient.Rcpt(rcpt); err != nil {
+				rcptSendErr.Reason = ErrSMTPRcptTo
+				rcptSendErr.errlist = append(rcptSendErr.errlist, err)
+				rcptSendErr.rcpt = append(rcptSendErr.rcpt, rcpt)
+				rcptSendErr.isTemp = isTempError(err)
+				failed = true
+			}
+		}
+		if failed {
+			if resetSendErr := c.smtpClient.Reset(); resetSendErr != nil {
+				returnErr = errors.Join(returnErr, resetSendErr)
+			}
+			message.sendError = rcptSendErr
+			returnErr = errors.Join(returnErr, message.sendError)
+			continue
+		}
+		writer, err := c.smtpClient.Data()
+		if err != nil {
+			message.sendError = &SendError{Reason: ErrSMTPData, errlist: []error{err}, isTemp: isTempError(err)}
+			returnErr = errors.Join(returnErr, message.sendError)
+			continue
+		}
+		_, err = message.WriteTo(writer)
+		if err != nil {
+			message.sendError = &SendError{Reason: ErrWriteContent, errlist: []error{err}, isTemp: isTempError(err)}
+			returnErr = errors.Join(returnErr, message.sendError)
+			continue
+		}
+		message.isDelivered = true
 
-	for id, message := range messages {
+		if err = writer.Close(); err != nil {
-		if sendErr := c.sendSingleMsg(message); sendErr != nil {
+			message.sendError = &SendError{Reason: ErrSMTPDataClose, errlist: []error{err}, isTemp: isTempError(err)}
-			messages[id].sendError = sendErr
+			returnErr = errors.Join(returnErr, message.sendError)
-			errs = append(errs, sendErr)
+			continue
+		}
+
+		if err = c.Reset(); err != nil {
+			message.sendError = &SendError{Reason: ErrSMTPReset, errlist: []error{err}, isTemp: isTempError(err)}
+			returnErr = errors.Join(returnErr, message.sendError)
+			continue
+		}
+		if err = c.checkConn(); err != nil {
+			message.sendError = &SendError{Reason: ErrConnCheck, errlist: []error{err}, isTemp: isTempError(err)}
+			returnErr = errors.Join(returnErr, message.sendError)
 		}
 	}
 

client_test.go

@@ -5,7 +5,6 @@
 package mail
 
 import (
-	"bufio"
 	"context"
 	"crypto/tls"
 	"errors"
@@ -22,18 +21,11 @@ import (
 	"github.com/wneessen/go-mail/smtp"
 )
 
-const (
+// DefaultHost is used as default hostname for the Client
-	// DefaultHost is used as default hostname for the Client
+const DefaultHost = "localhost"
-	DefaultHost = "localhost"
+
-	// TestRcpt is a trash mail address to send test mails to
+// TestRcpt
-	TestRcpt = "go-mail@mytrashmailer.com"
+const TestRcpt = "go-mail@mytrashmailer.com"
-	// TestServerProto is the protocol used for the simple SMTP test server
-	TestServerProto = "tcp"
-	// TestServerAddr is the address the simple SMTP test server listens on
-	TestServerAddr = "127.0.0.1"
-	// TestServerPortBase is the base port for the simple SMTP test server
-	TestServerPortBase = 2025
-)
 
 // TestNewClient tests the NewClient() method with its default options
 func TestNewClient(t *testing.T) {
@@ -637,7 +629,7 @@ func TestClient_DialWithContext(t *testing.T) {
 // TestClient_DialWithContext_Fallback tests the Client.DialWithContext method with the fallback
 // port functionality
 func TestClient_DialWithContext_Fallback(t *testing.T) {
-	c, err := getTestConnectionNoTestPort(true)
+	c, err := getTestConnection(true)
 	if err != nil {
 		t.Skipf("failed to create test client: %s. Skipping tests", err)
 	}
@@ -1259,475 +1251,6 @@ func TestClient_DialAndSendWithContext_withSendError(t *testing.T) {
 	}
 }
 
-func TestClient_SendErrorNoEncoding(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-
-	featureSet := "250-AUTH PLAIN\r\n250-DSN\r\n250 SMTPUTF8"
-	serverPort := TestServerPortBase + 1
-	go func() {
-		if err := simpleSMTPServer(ctx, featureSet, false, serverPort); err != nil {
-			t.Errorf("failed to start test server: %s", err)
-			return
-		}
-	}()
-	time.Sleep(time.Millisecond * 300)
-
-	message := NewMsg()
-	if err := message.From("valid-from@domain.tld"); err != nil {
-		t.Errorf("failed to set FROM address: %s", err)
-		return
-	}
-	if err := message.To("valid-to@domain.tld"); err != nil {
-		t.Errorf("failed to set TO address: %s", err)
-		return
-	}
-	message.Subject("Test subject")
-	message.SetBodyString(TypeTextPlain, "Test body")
-	message.SetMessageIDWithValue("this.is.a.message.id")
-	message.SetEncoding(NoEncoding)
-
-	client, err := NewClient(TestServerAddr, WithPort(serverPort),
-		WithTLSPortPolicy(NoTLS), WithSMTPAuth(SMTPAuthPlain),
-		WithUsername("toni@tester.com"),
-		WithPassword("V3ryS3cr3t+"))
-	if err != nil {
-		t.Errorf("unable to create new client: %s", err)
-	}
-	if err = client.DialWithContext(context.Background()); err != nil {
-		t.Errorf("failed to dial to test server: %s", err)
-	}
-	if err = client.Send(message); err == nil {
-		t.Error("expected Send() to fail but didn't")
-	}
-
-	var sendErr *SendError
-	if !errors.As(err, &sendErr) {
-		t.Errorf("expected *SendError type as returned error, but got %T", sendErr)
-	}
-	if errors.As(err, &sendErr) {
-		if sendErr.IsTemp() {
-			t.Errorf("expected permanent error but IsTemp() returned true")
-		}
-		if sendErr.Reason != ErrNoUnencoded {
-			t.Errorf("expected ErrNoUnencoded error, but got %s", sendErr.Reason)
-		}
-		if !strings.EqualFold(sendErr.MessageID(), "<this.is.a.message.id>") {
-			t.Errorf("expected message ID: %q, but got %q", "<this.is.a.message.id>",
-				sendErr.MessageID())
-		}
-		if sendErr.Msg() == nil {
-			t.Errorf("expected message to be set, but got nil")
-		}
-	}
-
-	if err = client.Close(); err != nil {
-		t.Errorf("failed to close server connection: %s", err)
-	}
-}
-
-func TestClient_SendErrorMailFrom(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-
-	serverPort := TestServerPortBase + 2
-	featureSet := "250-AUTH PLAIN\r\n250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
-	go func() {
-		if err := simpleSMTPServer(ctx, featureSet, false, serverPort); err != nil {
-			t.Errorf("failed to start test server: %s", err)
-			return
-		}
-	}()
-	time.Sleep(time.Millisecond * 300)
-
-	message := NewMsg()
-	if err := message.From("invalid-from@domain.tld"); err != nil {
-		t.Errorf("failed to set FROM address: %s", err)
-		return
-	}
-	if err := message.To("valid-to@domain.tld"); err != nil {
-		t.Errorf("failed to set TO address: %s", err)
-		return
-	}
-	message.Subject("Test subject")
-	message.SetBodyString(TypeTextPlain, "Test body")
-	message.SetMessageIDWithValue("this.is.a.message.id")
-
-	client, err := NewClient(TestServerAddr, WithPort(serverPort),
-		WithTLSPortPolicy(NoTLS), WithSMTPAuth(SMTPAuthPlain),
-		WithUsername("toni@tester.com"),
-		WithPassword("V3ryS3cr3t+"))
-	if err != nil {
-		t.Errorf("unable to create new client: %s", err)
-	}
-	if err = client.DialWithContext(context.Background()); err != nil {
-		t.Errorf("failed to dial to test server: %s", err)
-	}
-	if err = client.Send(message); err == nil {
-		t.Error("expected Send() to fail but didn't")
-	}
-
-	var sendErr *SendError
-	if !errors.As(err, &sendErr) {
-		t.Errorf("expected *SendError type as returned error, but got %T", sendErr)
-	}
-	if errors.As(err, &sendErr) {
-		if sendErr.IsTemp() {
-			t.Errorf("expected permanent error but IsTemp() returned true")
-		}
-		if sendErr.Reason != ErrSMTPMailFrom {
-			t.Errorf("expected ErrSMTPMailFrom error, but got %s", sendErr.Reason)
-		}
-		if !strings.EqualFold(sendErr.MessageID(), "<this.is.a.message.id>") {
-			t.Errorf("expected message ID: %q, but got %q", "<this.is.a.message.id>",
-				sendErr.MessageID())
-		}
-		if sendErr.Msg() == nil {
-			t.Errorf("expected message to be set, but got nil")
-		}
-	}
-
-	if err = client.Close(); err != nil {
-		t.Errorf("failed to close server connection: %s", err)
-	}
-}
-
-func TestClient_SendErrorMailFromReset(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-
-	serverPort := TestServerPortBase + 3
-	featureSet := "250-AUTH PLAIN\r\n250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
-	go func() {
-		if err := simpleSMTPServer(ctx, featureSet, true, serverPort); err != nil {
-			t.Errorf("failed to start test server: %s", err)
-			return
-		}
-	}()
-	time.Sleep(time.Millisecond * 300)
-
-	message := NewMsg()
-	if err := message.From("invalid-from@domain.tld"); err != nil {
-		t.Errorf("failed to set FROM address: %s", err)
-		return
-	}
-	if err := message.To("valid-to@domain.tld"); err != nil {
-		t.Errorf("failed to set TO address: %s", err)
-		return
-	}
-	message.Subject("Test subject")
-	message.SetBodyString(TypeTextPlain, "Test body")
-	message.SetMessageIDWithValue("this.is.a.message.id")
-
-	client, err := NewClient(TestServerAddr, WithPort(serverPort),
-		WithTLSPortPolicy(NoTLS), WithSMTPAuth(SMTPAuthPlain),
-		WithUsername("toni@tester.com"),
-		WithPassword("V3ryS3cr3t+"))
-	if err != nil {
-		t.Errorf("unable to create new client: %s", err)
-	}
-	if err = client.DialWithContext(context.Background()); err != nil {
-		t.Errorf("failed to dial to test server: %s", err)
-	}
-	if err = client.Send(message); err == nil {
-		t.Error("expected Send() to fail but didn't")
-	}
-
-	var sendErr *SendError
-	if !errors.As(err, &sendErr) {
-		t.Errorf("expected *SendError type as returned error, but got %T", sendErr)
-	}
-	if errors.As(err, &sendErr) {
-		if sendErr.IsTemp() {
-			t.Errorf("expected permanent error but IsTemp() returned true")
-		}
-		if sendErr.Reason != ErrSMTPMailFrom {
-			t.Errorf("expected ErrSMTPMailFrom error, but got %s", sendErr.Reason)
-		}
-		if !strings.EqualFold(sendErr.MessageID(), "<this.is.a.message.id>") {
-			t.Errorf("expected message ID: %q, but got %q", "<this.is.a.message.id>",
-				sendErr.MessageID())
-		}
-		if len(sendErr.errlist) != 2 {
-			t.Errorf("expected 2 errors, but got %d", len(sendErr.errlist))
-			return
-		}
-		if !strings.EqualFold(sendErr.errlist[0].Error(), "503 5.1.2 Invalid from: <invalid-from@domain.tld>") {
-			t.Errorf("expected error: %q, but got %q",
-				"503 5.1.2 Invalid from: <invalid-from@domain.tld>", sendErr.errlist[0].Error())
-		}
-		if !strings.EqualFold(sendErr.errlist[1].Error(), "500 5.1.2 Error: reset failed") {
-			t.Errorf("expected error: %q, but got %q",
-				"500 5.1.2 Error: reset failed", sendErr.errlist[1].Error())
-		}
-	}
-
-	if err = client.Close(); err != nil {
-		t.Errorf("failed to close server connection: %s", err)
-	}
-}
-
-func TestClient_SendErrorToReset(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-
-	serverPort := TestServerPortBase + 4
-	featureSet := "250-AUTH PLAIN\r\n250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
-	go func() {
-		if err := simpleSMTPServer(ctx, featureSet, true, serverPort); err != nil {
-			t.Errorf("failed to start test server: %s", err)
-			return
-		}
-	}()
-	time.Sleep(time.Millisecond * 300)
-
-	message := NewMsg()
-	if err := message.From("valid-from@domain.tld"); err != nil {
-		t.Errorf("failed to set FROM address: %s", err)
-		return
-	}
-	if err := message.To("invalid-to@domain.tld"); err != nil {
-		t.Errorf("failed to set TO address: %s", err)
-		return
-	}
-	message.Subject("Test subject")
-	message.SetBodyString(TypeTextPlain, "Test body")
-	message.SetMessageIDWithValue("this.is.a.message.id")
-
-	client, err := NewClient(TestServerAddr, WithPort(serverPort),
-		WithTLSPortPolicy(NoTLS), WithSMTPAuth(SMTPAuthPlain),
-		WithUsername("toni@tester.com"),
-		WithPassword("V3ryS3cr3t+"))
-	if err != nil {
-		t.Errorf("unable to create new client: %s", err)
-	}
-	if err = client.DialWithContext(context.Background()); err != nil {
-		t.Errorf("failed to dial to test server: %s", err)
-	}
-	if err = client.Send(message); err == nil {
-		t.Error("expected Send() to fail but didn't")
-	}
-
-	var sendErr *SendError
-	if !errors.As(err, &sendErr) {
-		t.Errorf("expected *SendError type as returned error, but got %T", sendErr)
-	}
-	if errors.As(err, &sendErr) {
-		if sendErr.IsTemp() {
-			t.Errorf("expected permanent error but IsTemp() returned true")
-		}
-		if sendErr.Reason != ErrSMTPRcptTo {
-			t.Errorf("expected ErrSMTPRcptTo error, but got %s", sendErr.Reason)
-		}
-		if !strings.EqualFold(sendErr.MessageID(), "<this.is.a.message.id>") {
-			t.Errorf("expected message ID: %q, but got %q", "<this.is.a.message.id>",
-				sendErr.MessageID())
-		}
-		if len(sendErr.errlist) != 2 {
-			t.Errorf("expected 2 errors, but got %d", len(sendErr.errlist))
-			return
-		}
-		if !strings.EqualFold(sendErr.errlist[0].Error(), "500 5.1.2 Invalid to: <invalid-to@domain.tld>") {
-			t.Errorf("expected error: %q, but got %q",
-				"500 5.1.2 Invalid to: <invalid-to@domain.tld>", sendErr.errlist[0].Error())
-		}
-		if !strings.EqualFold(sendErr.errlist[1].Error(), "500 5.1.2 Error: reset failed") {
-			t.Errorf("expected error: %q, but got %q",
-				"500 5.1.2 Error: reset failed", sendErr.errlist[1].Error())
-		}
-	}
-
-	if err = client.Close(); err != nil {
-		t.Errorf("failed to close server connection: %s", err)
-	}
-}
-
-func TestClient_SendErrorDataClose(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-
-	serverPort := TestServerPortBase + 5
-	featureSet := "250-AUTH PLAIN\r\n250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
-	go func() {
-		if err := simpleSMTPServer(ctx, featureSet, false, serverPort); err != nil {
-			t.Errorf("failed to start test server: %s", err)
-			return
-		}
-	}()
-	time.Sleep(time.Millisecond * 300)
-
-	message := NewMsg()
-	if err := message.From("valid-from@domain.tld"); err != nil {
-		t.Errorf("failed to set FROM address: %s", err)
-		return
-	}
-	if err := message.To("valid-to@domain.tld"); err != nil {
-		t.Errorf("failed to set TO address: %s", err)
-		return
-	}
-	message.Subject("Test subject")
-	message.SetBodyString(TypeTextPlain, "DATA close should fail")
-	message.SetMessageIDWithValue("this.is.a.message.id")
-
-	client, err := NewClient(TestServerAddr, WithPort(serverPort),
-		WithTLSPortPolicy(NoTLS), WithSMTPAuth(SMTPAuthPlain),
-		WithUsername("toni@tester.com"),
-		WithPassword("V3ryS3cr3t+"))
-	if err != nil {
-		t.Errorf("unable to create new client: %s", err)
-	}
-	if err = client.DialWithContext(context.Background()); err != nil {
-		t.Errorf("failed to dial to test server: %s", err)
-	}
-	if err = client.Send(message); err == nil {
-		t.Error("expected Send() to fail but didn't")
-	}
-
-	var sendErr *SendError
-	if !errors.As(err, &sendErr) {
-		t.Errorf("expected *SendError type as returned error, but got %T", sendErr)
-	}
-	if errors.As(err, &sendErr) {
-		if sendErr.IsTemp() {
-			t.Errorf("expected permanent error but IsTemp() returned true")
-		}
-		if sendErr.Reason != ErrSMTPDataClose {
-			t.Errorf("expected ErrSMTPDataClose error, but got %s", sendErr.Reason)
-		}
-		if !strings.EqualFold(sendErr.MessageID(), "<this.is.a.message.id>") {
-			t.Errorf("expected message ID: %q, but got %q", "<this.is.a.message.id>",
-				sendErr.MessageID())
-		}
-	}
-
-	if err = client.Close(); err != nil {
-		t.Errorf("failed to close server connection: %s", err)
-	}
-}
-
-func TestClient_SendErrorDataWrite(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-
-	serverPort := TestServerPortBase + 6
-	featureSet := "250-AUTH PLAIN\r\n250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
-	go func() {
-		if err := simpleSMTPServer(ctx, featureSet, false, serverPort); err != nil {
-			t.Errorf("failed to start test server: %s", err)
-			return
-		}
-	}()
-	time.Sleep(time.Millisecond * 300)
-
-	message := NewMsg()
-	if err := message.From("valid-from@domain.tld"); err != nil {
-		t.Errorf("failed to set FROM address: %s", err)
-		return
-	}
-	if err := message.To("valid-to@domain.tld"); err != nil {
-		t.Errorf("failed to set TO address: %s", err)
-		return
-	}
-	message.Subject("Test subject")
-	message.SetBodyString(TypeTextPlain, "DATA write should fail")
-	message.SetMessageIDWithValue("this.is.a.message.id")
-	message.SetGenHeader("X-Test-Header", "DATA write should fail")
-
-	client, err := NewClient(TestServerAddr, WithPort(serverPort),
-		WithTLSPortPolicy(NoTLS), WithSMTPAuth(SMTPAuthPlain),
-		WithUsername("toni@tester.com"),
-		WithPassword("V3ryS3cr3t+"))
-	if err != nil {
-		t.Errorf("unable to create new client: %s", err)
-	}
-	if err = client.DialWithContext(context.Background()); err != nil {
-		t.Errorf("failed to dial to test server: %s", err)
-	}
-	if err = client.Send(message); err == nil {
-		t.Error("expected Send() to fail but didn't")
-	}
-
-	var sendErr *SendError
-	if !errors.As(err, &sendErr) {
-		t.Errorf("expected *SendError type as returned error, but got %T", sendErr)
-	}
-	if errors.As(err, &sendErr) {
-		if sendErr.IsTemp() {
-			t.Errorf("expected permanent error but IsTemp() returned true")
-		}
-		if sendErr.Reason != ErrSMTPDataClose {
-			t.Errorf("expected ErrSMTPDataClose error, but got %s", sendErr.Reason)
-		}
-		if !strings.EqualFold(sendErr.MessageID(), "<this.is.a.message.id>") {
-			t.Errorf("expected message ID: %q, but got %q", "<this.is.a.message.id>",
-				sendErr.MessageID())
-		}
-	}
-}
-
-func TestClient_SendErrorReset(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-
-	serverPort := TestServerPortBase + 7
-	featureSet := "250-AUTH PLAIN\r\n250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
-	go func() {
-		if err := simpleSMTPServer(ctx, featureSet, true, serverPort); err != nil {
-			t.Errorf("failed to start test server: %s", err)
-			return
-		}
-	}()
-	time.Sleep(time.Millisecond * 300)
-
-	message := NewMsg()
-	if err := message.From("valid-from@domain.tld"); err != nil {
-		t.Errorf("failed to set FROM address: %s", err)
-		return
-	}
-	if err := message.To("valid-to@domain.tld"); err != nil {
-		t.Errorf("failed to set TO address: %s", err)
-		return
-	}
-	message.Subject("Test subject")
-	message.SetBodyString(TypeTextPlain, "Test body")
-	message.SetMessageIDWithValue("this.is.a.message.id")
-
-	client, err := NewClient(TestServerAddr, WithPort(serverPort),
-		WithTLSPortPolicy(NoTLS), WithSMTPAuth(SMTPAuthPlain),
-		WithUsername("toni@tester.com"),
-		WithPassword("V3ryS3cr3t+"))
-	if err != nil {
-		t.Errorf("unable to create new client: %s", err)
-	}
-	if err = client.DialWithContext(context.Background()); err != nil {
-		t.Errorf("failed to dial to test server: %s", err)
-	}
-	if err = client.Send(message); err == nil {
-		t.Error("expected Send() to fail but didn't")
-	}
-
-	var sendErr *SendError
-	if !errors.As(err, &sendErr) {
-		t.Errorf("expected *SendError type as returned error, but got %T", sendErr)
-	}
-	if errors.As(err, &sendErr) {
-		if sendErr.IsTemp() {
-			t.Errorf("expected permanent error but IsTemp() returned true")
-		}
-		if sendErr.Reason != ErrSMTPReset {
-			t.Errorf("expected ErrSMTPReset error, but got %s", sendErr.Reason)
-		}
-		if !strings.EqualFold(sendErr.MessageID(), "<this.is.a.message.id>") {
-			t.Errorf("expected message ID: %q, but got %q", "<this.is.a.message.id>",
-				sendErr.MessageID())
-		}
-	}
-
-	if err = client.Close(); err != nil {
-		t.Errorf("failed to close server connection: %s", err)
-	}
-}
-
 // getTestConnection takes environment variables to establish a connection to a real
 // SMTP server to test all functionality that requires a connection
 func getTestConnection(auth bool) (*Client, error) {
@@ -1779,50 +1302,6 @@ func getTestConnection(auth bool) (*Client, error) {
 	return c, nil
 }
 
-// getTestConnectionNoTestPort takes environment variables (except the port) to establish a
-// connection to a real SMTP server to test all functionality that requires a connection
-func getTestConnectionNoTestPort(auth bool) (*Client, error) {
-	if os.Getenv("TEST_SKIP_ONLINE") != "" {
-		return nil, fmt.Errorf("env variable TEST_SKIP_ONLINE is set. Skipping online tests")
-	}
-	th := os.Getenv("TEST_HOST")
-	if th == "" {
-		return nil, fmt.Errorf("no TEST_HOST set")
-	}
-	sv := false
-	if sve := os.Getenv("TEST_TLS_SKIP_VERIFY"); sve != "" {
-		sv = true
-	}
-	c, err := NewClient(th)
-	if err != nil {
-		return c, err
-	}
-	c.tlsconfig.InsecureSkipVerify = sv
-	if auth {
-		st := os.Getenv("TEST_SMTPAUTH_TYPE")
-		if st != "" {
-			c.SetSMTPAuth(SMTPAuthType(st))
-		}
-		u := os.Getenv("TEST_SMTPAUTH_USER")
-		if u != "" {
-			c.SetUsername(u)
-		}
-		p := os.Getenv("TEST_SMTPAUTH_PASS")
-		if p != "" {
-			c.SetPassword(p)
-		}
-		// We don't want to log authentication data in tests
-		c.SetDebugLog(false)
-	}
-	if err := c.DialWithContext(context.Background()); err != nil {
-		return c, fmt.Errorf("connection to test server failed: %w", err)
-	}
-	if err := c.Close(); err != nil {
-		return c, fmt.Errorf("disconnect from test server failed: %w", err)
-	}
-	return c, nil
-}
-
 // getTestClient takes environment variables to establish a client without connecting
 // to the SMTP server
 func getTestClient(auth bool) (*Client, error) {
@@ -1878,14 +1357,7 @@ func getTestConnectionWithDSN(auth bool) (*Client, error) {
 	if th == "" {
 		return nil, fmt.Errorf("no TEST_HOST set")
 	}
-	tp := 25
+	c, err := NewClient(th, WithDSN())
-	if tps := os.Getenv("TEST_PORT"); tps != "" {
-		tpi, err := strconv.Atoi(tps)
-		if err == nil {
-			tp = tpi
-		}
-	}
-	c, err := NewClient(th, WithDSN(), WithPort(tp))
 	if err != nil {
 		return c, err
 	}
@@ -2022,155 +1494,3 @@ func (f faker) RemoteAddr() net.Addr             { return nil }
 func (f faker) SetDeadline(time.Time) error      { return nil }
 func (f faker) SetReadDeadline(time.Time) error  { return nil }
 func (f faker) SetWriteDeadline(time.Time) error { return nil }
-
-// simpleSMTPServer starts a simple TCP server that resonds to SMTP commands.
-// The provided featureSet represents in what the server responds to EHLO command
-// failReset controls if a RSET succeeds
-func simpleSMTPServer(ctx context.Context, featureSet string, failReset bool, port int) error {
-	listener, err := net.Listen(TestServerProto, fmt.Sprintf("%s:%d", TestServerAddr, port))
-	if err != nil {
-		return fmt.Errorf("unable to listen on %s://%s: %w", TestServerProto, TestServerAddr, err)
-	}
-
-	defer func() {
-		if err := listener.Close(); err != nil {
-			fmt.Printf("unable to close listener: %s\n", err)
-			os.Exit(1)
-		}
-	}()
-
-	for {
-		select {
-		case <-ctx.Done():
-			return nil
-		default:
-			connection, err := listener.Accept()
-			var opErr *net.OpError
-			if err != nil {
-				if errors.As(err, &opErr) && opErr.Temporary() {
-					continue
-				}
-				return fmt.Errorf("unable to accept connection: %w", err)
-			}
-			handleTestServerConnection(connection, featureSet, failReset)
-		}
-	}
-}
-
-func handleTestServerConnection(connection net.Conn, featureSet string, failReset bool) {
-	defer func() {
-		if err := connection.Close(); err != nil {
-			fmt.Printf("unable to close connection: %s\n", err)
-		}
-	}()
-
-	reader := bufio.NewReader(connection)
-	writer := bufio.NewWriter(connection)
-
-	writeLine := func(data string) error {
-		_, err := writer.WriteString(data + "\r\n")
-		if err != nil {
-			return fmt.Errorf("unable to write line: %w", err)
-		}
-		return writer.Flush()
-	}
-	writeOK := func() {
-		_ = writeLine("250 2.0.0 OK")
-	}
-
-	if err := writeLine("220 go-mail test server ready ESMTP"); err != nil {
-		fmt.Printf("unable to write to client: %s\n", err)
-		return
-	}
-
-	data, err := reader.ReadString('\n')
-	if err != nil {
-		fmt.Printf("unable to read from connection: %s\n", err)
-		return
-	}
-	if !strings.HasPrefix(data, "EHLO") && !strings.HasPrefix(data, "HELO") {
-		fmt.Printf("expected EHLO, got %q", data)
-		return
-	}
-	if err = writeLine("250-localhost.localdomain\r\n" + featureSet); err != nil {
-		fmt.Printf("unable to write to connection: %s\n", err)
-		return
-	}
-
-	for {
-		data, err = reader.ReadString('\n')
-		if err != nil {
-			if errors.Is(err, io.EOF) {
-				break
-			}
-			fmt.Println("Error reading data:", err)
-			break
-		}
-
-		var datastring string
-		data = strings.TrimSpace(data)
-		switch {
-		case strings.HasPrefix(data, "MAIL FROM:"):
-			from := strings.TrimPrefix(data, "MAIL FROM:")
-			from = strings.ReplaceAll(from, "BODY=8BITMIME", "")
-			from = strings.ReplaceAll(from, "SMTPUTF8", "")
-			from = strings.TrimSpace(from)
-			if !strings.EqualFold(from, "<valid-from@domain.tld>") {
-				_ = writeLine(fmt.Sprintf("503 5.1.2 Invalid from: %s", from))
-				break
-			}
-			writeOK()
-		case strings.HasPrefix(data, "RCPT TO:"):
-			to := strings.TrimPrefix(data, "RCPT TO:")
-			to = strings.TrimSpace(to)
-			if !strings.EqualFold(to, "<valid-to@domain.tld>") {
-				_ = writeLine(fmt.Sprintf("500 5.1.2 Invalid to: %s", to))
-				break
-			}
-			writeOK()
-		case strings.HasPrefix(data, "AUTH PLAIN"):
-			auth := strings.TrimPrefix(data, "AUTH PLAIN ")
-			if !strings.EqualFold(auth, "AHRvbmlAdGVzdGVyLmNvbQBWM3J5UzNjcjN0Kw==") {
-				_ = writeLine("535 5.7.8 Error: authentication failed")
-				break
-			}
-			_ = writeLine("235 2.7.0 Authentication successful")
-		case strings.EqualFold(data, "DATA"):
-			_ = writeLine("354 End data with <CR><LF>.<CR><LF>")
-			for {
-				ddata, derr := reader.ReadString('\n')
-				if derr != nil {
-					fmt.Printf("failed to read DATA data from connection: %s\n", derr)
-					break
-				}
-				ddata = strings.TrimSpace(ddata)
-				if strings.EqualFold(ddata, "DATA write should fail") {
-					_ = writeLine("500 5.0.0 Error during DATA transmission")
-					break
-				}
-				if ddata == "." {
-					if strings.Contains(datastring, "DATA close should fail") {
-						_ = writeLine("500 5.0.0 Error during DATA closing")
-						break
-					}
-					_ = writeLine("250 2.0.0 Ok: queued as 1234567890")
-					break
-				}
-				datastring += ddata + "\n"
-			}
-		case strings.EqualFold(data, "noop"),
-			strings.EqualFold(data, "vrfy"):
-			writeOK()
-		case strings.EqualFold(data, "rset"):
-			if failReset {
-				_ = writeLine("500 5.1.2 Error: reset failed")
-				break
-			}
-			writeOK()
-		case strings.EqualFold(data, "quit"):
-			_ = writeLine("221 2.0.0 Bye")
-		default:
-			_ = writeLine("500 5.5.2 Error: bad syntax")
-		}
-	}
-}

connpool.go

@@ -1,89 +0,0 @@
-// SPDX-FileCopyrightText: 2022-2024 The go-mail Authors
-//
-// SPDX-License-Identifier: MIT
-
-package mail
-
-import (
-	"errors"
-	"net"
-	"sync"
-)
-
-// Parts of the connection pool code is forked from https://github.com/fatih/pool/
-// Thanks to Fatih Arslan and the project contributors for providing this great
-// concurrency template.
-
-var (
-	ErrPoolInvalidCap = errors.New("invalid connection pool capacity settings")
-)
-
-// Pool interface describes a connection pool implementation. A Pool is
-// thread-/go-routine safe.
-type Pool interface {
-	// Get returns a new connection from the pool. Closing the connections returns
-	// it back into the Pool. Closing a connection when the Pool is destroyed or
-	// full will be counted as an error.
-	Get() (net.Conn, error)
-
-	// Close closes the pool and all its connections. After Close() the pool is
-	// no longer usable.
-	Close()
-
-	// Len returns the current number of connections of the pool.
-	Len() int
-}
-
-// connPool implements the Pool interface
-type connPool struct {
-	// mutex is used to synchronize access to the connection pool to ensure thread-safe operations
-	mutex sync.RWMutex
-	// conns is a channel used to manage and distribute net.Conn objects within the connection pool
-	conns chan net.Conn
-	// dialCtx represents the actual net.Conn returned by the DialContextFunc
-	dialCtx DialContextFunc
-}
-
-// NewConnPool returns a new pool based on buffered channels with an initial
-// capacity and maximum capacity. The DialContextFunc is used when the initial
-// capacity is greater than zero to fill the pool. A zero initialCap doesn't
-// fill the Pool until a new Get() is called. During a Get(), if there is no
-// new connection available in the pool, a new connection will be created via
-// the corresponding DialContextFunc() method.
-func NewConnPool(initialCap, maxCap int, dialCtxFunc DialContextFunc) (Pool, error) {
-	if initialCap < 0 || maxCap <= 0 || initialCap > maxCap {
-		return nil, ErrPoolInvalidCap
-	}
-
-	pool := &connPool{
-		conns:   make(chan net.Conn, maxCap),
-		dialCtx: dialCtxFunc,
-	}
-
-	// create initial connections, if something goes wrong,
-	// just close the pool error out.
-	for i := 0; i < initialCap; i++ {
-		/*
-			conn, err := dialCtxFunc()
-			if err != nil {
-				pool.Close()
-				return nil, fmt.Errorf("factory is not able to fill the pool: %s", err)
-			}
-			c.conns <- conn
-
-		*/
-	}
-
-	return pool, nil
-}
-
-func (c *connPool) Get() (net.Conn, error) {
-	return nil, nil
-}
-func (c *connPool) Close() {
-	return
-}
-
-func (c *connPool) Len() int {
-	return 0
-}

msg.go

@@ -467,8 +467,8 @@ func (m *Msg) SetMessageID() {
 	if err != nil {
 		hostname = "localhost.localdomain"
 	}
-	randNumPrimary := randNum(100000000)
+	randNumPrimary, _ := randNum(100000000)
-	randNumSecondary := randNum(10000)
+	randNumSecondary, _ := randNum(10000)
 	randString, _ := randomStringSecure(17)
 	procID := os.Getpid() * randNumSecondary
 	messageID := fmt.Sprintf("%d.%d%d.%s@%s", procID, randNumPrimary, randNumSecondary,
@@ -476,17 +476,6 @@ func (m *Msg) SetMessageID() {
 	m.SetMessageIDWithValue(messageID)
 }
 
-// GetMessageID returns the message ID of the Msg as string value. If no message ID
-// is set, an empty string will be returned
-func (m *Msg) GetMessageID() string {
-	if msgidheader, ok := m.genHeader[HeaderMessageID]; ok {
-		if len(msgidheader) > 0 {
-			return msgidheader[0]
-		}
-	}
-	return ""
-}
-
 // SetMessageIDWithValue sets the message id for the mail
 func (m *Msg) SetMessageIDWithValue(messageID string) {
 	m.SetGenHeader(HeaderMessageID, fmt.Sprintf("<%s>", messageID))

msg_nowin_test.go

@@ -61,25 +61,3 @@ func TestMsg_WriteToSendmail(t *testing.T) {
 		t.Errorf("WriteToSendmail failed: %s", err)
 	}
 }
-
-func TestMsg_WriteToTempFileFailed(t *testing.T) {
-	m := NewMsg()
-	_ = m.From("Toni Tester <tester@example.com>")
-	_ = m.To("Ellenor Tester <ellinor@example.com>")
-	m.SetBodyString(TypeTextPlain, "This is a test")
-
-	curTmpDir := os.Getenv("TMPDIR")
-	defer func() {
-		if err := os.Setenv("TMPDIR", curTmpDir); err != nil {
-			t.Errorf("failed to set TMPDIR environment variable: %s", err)
-		}
-	}()
-
-	if err := os.Setenv("TMPDIR", "/invalid/directory/that/does/not/exist"); err != nil {
-		t.Errorf("failed to set TMPDIR environment variable: %s", err)
-	}
-	_, err := m.WriteToTempFile()
-	if err == nil {
-		t.Errorf("WriteToTempFile() did not fail as expected")
-	}
-}

msg_test.go

@@ -786,11 +786,13 @@ func TestMsg_SetMessageIDWithValue(t *testing.T) {
 // TestMsg_SetMessageIDRandomness tests the randomness of Msg.SetMessageID methods
 func TestMsg_SetMessageIDRandomness(t *testing.T) {
 	var mids []string
-	for i := 0; i < 50_000; i++ {
+	for i := 0; i < 100; i++ {
 		m := NewMsg()
 		m.SetMessageID()
-		mid := m.GetMessageID()
+		mid := m.GetGenHeader(HeaderMessageID)
-		mids = append(mids, mid)
+		if len(mid) > 0 {
+			mids = append(mids, mid[0])
+		}
 	}
 	c := make(map[string]int)
 	for i := range mids {
@@ -803,21 +805,6 @@ func TestMsg_SetMessageIDRandomness(t *testing.T) {
 	}
 }
 
-func TestMsg_GetMessageID(t *testing.T) {
-	expected := "this.is.a.message.id"
-	msg := NewMsg()
-	msg.SetMessageIDWithValue(expected)
-	val := msg.GetMessageID()
-	if !strings.EqualFold(val, fmt.Sprintf("<%s>", expected)) {
-		t.Errorf("GetMessageID() failed. Expected: %s, got: %s", fmt.Sprintf("<%s>", expected), val)
-	}
-	msg.genHeader[HeaderMessageID] = nil
-	val = msg.GetMessageID()
-	if val != "" {
-		t.Errorf("GetMessageID() failed. Expected empty string, got: %s", val)
-	}
-}
-
 // TestMsg_FromFormat tests the FromFormat and EnvelopeFrom methods for the Msg object
 func TestMsg_FromFormat(t *testing.T) {
 	tests := []struct {

random.go

@@ -7,6 +7,8 @@ package mail
 import (
 	"crypto/rand"
 	"encoding/binary"
+	"fmt"
+	"math/big"
 	"strings"
 )
 
@@ -50,3 +52,23 @@ func randomStringSecure(length int) (string, error) {
 
 	return randString.String(), nil
 }
+
+// randNum returns a random number with a maximum value of length
+func randNum(length int) (int, error) {
+	if length <= 0 {
+		return 0, fmt.Errorf("provided number is <= 0: %d", length)
+	}
+	length64 := big.NewInt(int64(length))
+	if !length64.IsUint64() {
+		return 0, fmt.Errorf("big.NewInt() generation returned negative value: %d", length64)
+	}
+	randNum64, err := rand.Int(rand.Reader, length64)
+	if err != nil {
+		return 0, err
+	}
+	randomNum := int(randNum64.Int64())
+	if randomNum < 0 {
+		return 0, fmt.Errorf("generated random number does not fit as int64: %d", randNum64)
+	}
+	return randomNum, nil
+}

random_119.go

@@ -1,22 +0,0 @@
-// SPDX-FileCopyrightText: 2022-2023 The go-mail Authors
-//
-// SPDX-License-Identifier: MIT
-
-//go:build go1.19 && !go1.20
-// +build go1.19,!go1.20
-
-package mail
-
-import (
-	"math/rand"
-	"time"
-)
-
-// randNum returns a random number with a maximum value of length
-func randNum(maxval int) int {
-	if maxval <= 0 {
-		return 0
-	}
-	rand.Seed(time.Now().UnixNano())
-	return rand.Intn(maxval)
-}

random_121.go

@@ -1,20 +0,0 @@
-// SPDX-FileCopyrightText: 2022-2023 The go-mail Authors
-//
-// SPDX-License-Identifier: MIT
-
-//go:build go1.20 && !go1.22
-// +build go1.20,!go1.22
-
-package mail
-
-import (
-	"math/rand"
-)
-
-// randNum returns a random number with a maximum value of length
-func randNum(maxval int) int {
-	if maxval <= 0 {
-		return 0
-	}
-	return rand.Intn(maxval)
-}

random_122.go

@@ -1,22 +0,0 @@
-// SPDX-FileCopyrightText: 2022-2023 The go-mail Authors
-//
-// SPDX-License-Identifier: MIT
-
-//go:build go1.22
-// +build go1.22
-
-package mail
-
-import (
-	"math/rand/v2"
-)
-
-// randNum returns a random number with a maximum value of maxval.
-// go-mail compiled with Go 1.22+ will make use of the novel math/rand/v2 interface
-// Older versions of Go will use math/rand
-func randNum(maxval int) int {
-	if maxval <= 0 {
-		return 0
-	}
-	return rand.IntN(maxval)
-}

random_test.go

@@ -55,17 +55,16 @@ func TestRandomNum(t *testing.T) {
 
 	for _, tc := range tt {
 		t.Run(tc.testName, func(t *testing.T) {
-			rn := randNum(tc.max)
+			rn, err := randNum(tc.max)
+			if err != nil {
+				t.Errorf("random number generation failed: %s", err)
+			}
+			if rn < 0 {
+				t.Errorf("random number generation failed: %d is smaller than zero", rn)
+			}
 			if rn > tc.max {
 				t.Errorf("random number generation failed: %d is bigger than given value %d", rn, tc.max)
 			}
 		})
 	}
 }
-
-func TestRandomNumZero(t *testing.T) {
-	rn := randNum(0)
-	if rn != 0 {
-		t.Errorf("random number generation failed: %d is not zero", rn)
-	}
-}

senderror.go

@@ -56,11 +56,10 @@ const (
 
 // SendError is an error wrapper for delivery errors of the Msg
 type SendError struct {
-	affectedMsg *Msg
-	errlist     []error
-	isTemp      bool
-	rcpt        []string
 	Reason  SendErrReason
+	isTemp  bool
+	errlist []error
+	rcpt    []string
 }
 
 // SendErrReason represents a comparable reason on why the delivery failed
@@ -93,11 +92,6 @@ func (e *SendError) Error() string {
 			}
 		}
 	}
-	if e.affectedMsg != nil && e.affectedMsg.GetMessageID() != "" {
-		errMessage.WriteString(", affected message ID: ")
-		errMessage.WriteString(e.affectedMsg.GetMessageID())
-	}
-
 	return errMessage.String()
 }
 
@@ -118,23 +112,6 @@ func (e *SendError) IsTemp() bool {
 	return e.isTemp
 }
 
-// MessageID returns the message ID of the affected Msg that caused the error
-// If no message ID was set for the Msg, an empty string will be returned
-func (e *SendError) MessageID() string {
-	if e == nil || e.affectedMsg == nil {
-		return ""
-	}
-	return e.affectedMsg.GetMessageID()
-}
-
-// Msg returns the pointer to the affected message that caused the error
-func (e *SendError) Msg() *Msg {
-	if e == nil || e.affectedMsg == nil {
-		return nil
-	}
-	return e.affectedMsg
-}
-
 // String implements the Stringer interface for the SendErrReason
 func (r SendErrReason) String() string {
 	switch r {

senderror_test.go

@@ -83,96 +83,7 @@ func TestSendError_IsTemp(t *testing.T) {
 	}
 }
 
-func TestSendError_IsTempNil(t *testing.T) {
-	var se *SendError
-	if se.IsTemp() {
-		t.Error("expected false on nil-senderror")
-	}
-}
-
-func TestSendError_MessageID(t *testing.T) {
-	var se *SendError
-	err := returnSendError(ErrAmbiguous, false)
-	if !errors.As(err, &se) {
-		t.Errorf("error mismatch, expected error to be of type *SendError")
-		return
-	}
-	if errors.As(err, &se) {
-		if se.MessageID() == "" {
-			t.Errorf("sendError expected message-id, but got empty string")
-		}
-		if !strings.EqualFold(se.MessageID(), "<this.is.a.message.id>") {
-			t.Errorf("sendError message-id expected: %s, but got: %s", "<this.is.a.message.id>",
-				se.MessageID())
-		}
-	}
-}
-
-func TestSendError_MessageIDNil(t *testing.T) {
-	var se *SendError
-	if se.MessageID() != "" {
-		t.Error("expected empty string on nil-senderror")
-	}
-}
-
-func TestSendError_Msg(t *testing.T) {
-	var se *SendError
-	err := returnSendError(ErrAmbiguous, false)
-	if !errors.As(err, &se) {
-		t.Errorf("error mismatch, expected error to be of type *SendError")
-		return
-	}
-	if errors.As(err, &se) {
-		if se.Msg() == nil {
-			t.Errorf("sendError expected msg pointer, but got nil")
-		}
-		from := se.Msg().GetFromString()
-		if len(from) == 0 {
-			t.Errorf("sendError expected msg from, but got empty string")
-			return
-		}
-		if !strings.EqualFold(from[0], "<toni.tester@domain.tld>") {
-			t.Errorf("sendError message from expected: %s, but got: %s", "<toni.tester@domain.tld>",
-				from[0])
-		}
-	}
-}
-
-func TestSendError_MsgNil(t *testing.T) {
-	var se *SendError
-	if se.Msg() != nil {
-		t.Error("expected nil on nil-senderror")
-	}
-}
-
-func TestSendError_IsFail(t *testing.T) {
-	err1 := returnSendError(ErrAmbiguous, false)
-	err2 := returnSendError(ErrSMTPMailFrom, false)
-	if errors.Is(err1, err2) {
-		t.Errorf("error mismatch, ErrAmbiguous should not be equal to ErrSMTPMailFrom")
-	}
-}
-
-func TestSendError_ErrorMulti(t *testing.T) {
-	expected := `ambiguous reason, check Msg.SendError for message specific reasons, ` +
-		`affected recipient(s): <email1@domain.tld>, <email2@domain.tld>`
-	err := &SendError{
-		Reason: ErrAmbiguous, isTemp: false, affectedMsg: nil,
-		rcpt: []string{"<email1@domain.tld>", "<email2@domain.tld>"},
-	}
-	if err.Error() != expected {
-		t.Errorf("error mismatch, expected: %s, got: %s", expected, err.Error())
-	}
-}
-
 // returnSendError is a helper method to retunr a SendError with a specific reason
 func returnSendError(r SendErrReason, t bool) error {
-	message := NewMsg()
+	return &SendError{Reason: r, isTemp: t}
-	_ = message.From("toni.tester@domain.tld")
-	_ = message.To("tina.tester@domain.tld")
-	message.Subject("This is the subject")
-	message.SetBodyString(TypeTextPlain, "This is the message body")
-	message.SetMessageIDWithValue("this.is.a.message.id")
-
-	return &SendError{Reason: r, isTemp: t, affectedMsg: message}
 }