More progress... calling it a day.

.idea/workspace.xml

@@ -0,0 +1,112 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="AutoImportSettings">
+    <option name="autoReloadType" value="ALL" />
+  </component>
+  <component name="ChangeListManager">
+    <list default="true" id="b7733b42-c5ae-46b3-8a96-8b973d69a11d" name="Changes" comment="Calling it a day...">
+      <change afterPath="$PROJECT_DIR$/encoding.go" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/header.go" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/mailmsg.go" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/client_test.go" beforeDir="false" afterPath="$PROJECT_DIR$/client_test.go" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/cmd/main.go" beforeDir="false" afterPath="$PROJECT_DIR$/cmd/main.go" afterDir="false" />
+    </list>
+    <option name="SHOW_DIALOG" value="false" />
+    <option name="HIGHLIGHT_CONFLICTS" value="true" />
+    <option name="HIGHLIGHT_NON_ACTIVE_CHANGELIST" value="false" />
+    <option name="LAST_RESOLUTION" value="IGNORE" />
+  </component>
+  <component name="FileTemplateManagerImpl">
+    <option name="RECENT_TEMPLATES">
+      <list>
+        <option value="Go File" />
+      </list>
+    </option>
+  </component>
+  <component name="GOROOT" url="file://$PROJECT_DIR$/../../go1.17.8" />
+  <component name="Git.Settings">
+    <option name="RECENT_GIT_ROOT_PATH" value="$PROJECT_DIR$" />
+  </component>
+  <component name="MarkdownSettingsMigration">
+    <option name="stateVersion" value="1" />
+  </component>
+  <component name="ProjectId" id="25y1BKo9v06G2DMj9UoZG0ZxDb1" />
+  <component name="ProjectLevelVcsManager">
+    <OptionsSetting value="false" id="Update" />
+  </component>
+  <component name="ProjectViewState">
+    <option name="hideEmptyMiddlePackages" value="true" />
+    <option name="showLibraryContents" value="true" />
+  </component>
+  <component name="PropertiesComponent">
+    <property name="DefaultGoTemplateProperty" value="Go File" />
+    <property name="RunOnceActivity.OpenProjectViewOnStart" value="true" />
+    <property name="RunOnceActivity.ShowReadmeOnStart" value="true" />
+    <property name="TF_FMT" value="false" />
+    <property name="WebServerToolWindowFactoryState" value="true" />
+    <property name="go.format.on.save.advertiser.fired" value="true" />
+    <property name="go.formatter.settings.were.checked" value="true" />
+    <property name="go.import.settings.migrated" value="true" />
+    <property name="go.modules.go.list.on.any.changes.was.set" value="true" />
+    <property name="go.sdk.automatically.set" value="true" />
+    <property name="go.watchers.conflict.with.on.save.actions.check.performed" value="true" />
+    <property name="last_opened_file_path" value="$USER_HOME$" />
+    <property name="settings.editor.selected.configurable" value="go.vgo" />
+  </component>
+  <component name="RunManager">
+    <configuration default="true" type="GoApplicationRunConfiguration" factoryName="Go Application">
+      <module name="go-mail" />
+      <working_directory value="$PROJECT_DIR$" />
+      <go_parameters value="-i" />
+      <kind value="PACKAGE" />
+      <package value="go-mail" />
+      <directory value="$PROJECT_DIR$" />
+      <filePath value="$PROJECT_DIR$" />
+      <method v="2" />
+    </configuration>
+    <configuration default="true" type="GoTestRunConfiguration" factoryName="Go Test">
+      <module name="go-mail" />
+      <working_directory value="$PROJECT_DIR$" />
+      <go_parameters value="-i" />
+      <kind value="DIRECTORY" />
+      <package value="go-mail" />
+      <directory value="$PROJECT_DIR$" />
+      <filePath value="$PROJECT_DIR$" />
+      <framework value="gotest" />
+      <method v="2" />
+    </configuration>
+    <configuration name="go test github.com/wneessen/go-mail" type="GoTestRunConfiguration" factoryName="Go Test" nameIsGenerated="true">
+      <module name="go-mail" />
+      <working_directory value="$PROJECT_DIR$" />
+      <kind value="PACKAGE" />
+      <package value="github.com/wneessen/go-mail" />
+      <directory value="$PROJECT_DIR$" />
+      <filePath value="$PROJECT_DIR$" />
+      <framework value="gotest" />
+      <method v="2" />
+    </configuration>
+  </component>
+  <component name="SpellCheckerSettings" RuntimeDictionaries="0" Folders="0" CustomDictionaries="0" DefaultDictionary="application-level" UseSingleDictionary="true" transferred="true" />
+  <component name="TypeScriptGeneratedFilesManager">
+    <option name="version" value="3" />
+  </component>
+  <component name="Vcs.Log.Tabs.Properties">
+    <option name="TAB_STATES">
+      <map>
+        <entry key="MAIN">
+          <value>
+            <State />
+          </value>
+        </entry>
+      </map>
+    </option>
+  </component>
+  <component name="VcsManagerConfiguration">
+    <MESSAGE value="Makeing some progress..." />
+    <MESSAGE value="Calling it a day..." />
+    <option name="LAST_COMMIT_MESSAGE" value="Calling it a day..." />
+  </component>
+  <component name="VgoProject">
+    <integration-enabled>true</integration-enabled>
+  </component>
+</project>

client_test.go

@@ -101,3 +101,54 @@ func TestWithSSL(t *testing.T) {
 		})
 	}
 }
+
+// TestWithTLSPolicy tests the WithTLSPolicy() option for the NewClient() method
+func TestWithTLSPolicy(t *testing.T) {
+	tests := []struct {
+		name  string
+		value TLSPolicy
+		want  TLSPolicy
+	}{
+		{"Policy: TLSMandatory", TLSMandatory, TLSMandatory},
+		{"Policy: TLSOpportunistic", TLSOpportunistic, TLSOpportunistic},
+		{"Policy: NoTLS", NoTLS, NoTLS},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			c, err := NewClient(DefaultHost, WithTLSPolicy(tt.value))
+			if err != nil {
+				t.Errorf("failed to create new client: %s", err)
+				return
+			}
+			if c.tlspolicy != tt.want {
+				t.Errorf("failed to set TLSPolicy. Want: %s, got: %s", tt.want, c.tlspolicy)
+			}
+		})
+	}
+}
+
+// TestSetTLSPolicy tests the SetTLSPolicy() method for the Client object
+func TestSetTLSPolicy(t *testing.T) {
+	tests := []struct {
+		name  string
+		value TLSPolicy
+		want  TLSPolicy
+	}{
+		{"Policy: TLSMandatory", TLSMandatory, TLSMandatory},
+		{"Policy: TLSOpportunistic", TLSOpportunistic, TLSOpportunistic},
+		{"Policy: NoTLS", NoTLS, NoTLS},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			c, err := NewClient(DefaultHost, WithTLSPolicy(NoTLS))
+			if err != nil {
+				t.Errorf("failed to create new client: %s", err)
+				return
+			}
+			c.SetTLSPolicy(tt.value)
+			if c.tlspolicy != tt.want {
+				t.Errorf("failed to set TLSPolicy. Want: %s, got: %s", tt.want, c.tlspolicy)
+			}
+		})
+	}
+}

cmd/main.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"context"
-	"crypto/tls"
 	"fmt"
 	"github.com/wneessen/go-mail"
 	"os"
@@ -15,18 +14,12 @@ func main() {
 		fmt.Printf("$TEST_HOST env variable cannot be empty\n")
 		os.Exit(1)
 	}
-	c, err := mail.NewClient(th, mail.WithTimeout(time.Millisecond*500), mail.WithTLSPolicy(mail.TLSOpportunistic))
+	c, err := mail.NewClient(th, mail.WithTimeout(time.Millisecond*500))
 	if err != nil {
 		fmt.Printf("failed to create new client: %s\n", err)
 		os.Exit(1)
 	}
 	//c.SetTLSPolicy(mail.TLSMandatory)
-	tc := &tls.Config{
-		ServerName: th,
-		MinVersion: tls.VersionTLS10,
-		MaxVersion: tls.VersionTLS10,
-	}
-	c.SetTLSConfig(tc)
 
 	ctx, cfn := context.WithCancel(context.Background())
 	defer cfn()
@@ -35,6 +28,13 @@ func main() {
 		fmt.Printf("failed to dial: %s\n", err)
 		os.Exit(1)
 	}
-	fmt.Printf("Client: %+v\n", c)
+
-	fmt.Printf("StartTLS policy: %s\n", c.TLSPolicy())
+	m := mail.NewMsg()
+	m.From("wn@neessen.net")
+	m.To("test@test.de", "foo@bar.de", "blubb@blah.com")
+	m.Cc("cc@test.de", "cc@bar.de", "cc@blah.com")
+	m.SetMessageID()
+	m.SetBulk()
+	m.Header()
+
 }

encoding.go

@@ -0,0 +1,15 @@
+package mail
+
+// Encoding represents a MIME encoding scheme like quoted-printable or base64.
+type Encoding string
+
+const (
+	// EncodingB64 represents the Base64 encoding as specified in RFC 2045.
+	EncodingB64 Encoding = "base64"
+
+	// EncodingQP represents the "quoted-printable" encoding as specified in RFC 2045.
+	EncodingQP Encoding = "quoted-printable"
+
+	// NoEncoding avoids any character encoding (except of the mail headers)
+	NoEncoding Encoding = "8bit"
+)

header.go

@@ -0,0 +1,27 @@
+package mail
+
+// Header represents a mail header field name
+type Header string
+
+// List of common header field names
+const (
+	// HeaderFrom is the "From" header field
+	HeaderFrom Header = "From"
+
+	// HeaderTo is the "Receipient" header field
+	HeaderTo Header = "To"
+
+	// HeaderCc is the "Carbon Copy" header field
+	HeaderCc Header = "Cc"
+
+	// HeaderPrecedence is the "Precedence" header field
+	HeaderPrecedence Header = "Precedence"
+
+	// HeaderDate represents the "Date" field
+	// See: https://www.rfc-editor.org/rfc/rfc822#section-5.1
+	HeaderDate Header = "Date"
+
+	// HeaderMessageID represents the "Message-ID" field for message identification
+	// See: https://www.rfc-editor.org/rfc/rfc1036#section-2.1.5
+	HeaderMessageID Header = "Message-ID"
+)

mailmsg.go

@@ -0,0 +1,88 @@
+package mail
+
+import (
+	"fmt"
+	"math/rand"
+	"mime"
+	"os"
+	"time"
+)
+
+// Msg is the mail message struct
+type Msg struct {
+	// charset represents the charset of the mail (defaults to UTF-8)
+	charset string
+
+	// encoder represents a mime.WordEncoder from the std lib
+	encoder mime.WordEncoder
+
+	// header is a slice of strings that the different mail header fields
+	header map[Header][]string
+}
+
+// NewMsg returns a new Msg pointer
+func NewMsg() *Msg {
+	m := &Msg{
+		charset: "UTF-8",
+		header:  make(map[Header][]string),
+	}
+	return m
+}
+
+// SetHeader sets a header field of the Msg
+func (m *Msg) SetHeader(h Header, v ...string) {
+	switch h {
+	case HeaderFrom:
+		m.header[h] = []string{v[0]}
+	default:
+		m.header[h] = v
+	}
+}
+
+// From sets the From: address of the Msg
+func (m *Msg) From(f string) {
+	m.SetHeader(HeaderFrom, f)
+}
+
+// To sets the To: addresses of the Msg
+func (m *Msg) To(t ...string) {
+	m.SetHeader(HeaderTo, t...)
+}
+
+// Cc sets the Cc: addresses of the Msg
+func (m *Msg) Cc(c ...string) {
+	m.SetHeader(HeaderCc, c...)
+}
+
+// SetMessageID generates a random message id for the mail
+func (m *Msg) SetMessageID() {
+	hn, err := os.Hostname()
+	if err != nil {
+		hn = "localhost.localdomain"
+	}
+	ct := time.Now().UnixMicro()
+	r := rand.New(rand.NewSource(ct))
+	rn := r.Int()
+	pid := os.Getpid()
+
+	mid := fmt.Sprintf("%d.%d.%d@%s", pid, rn, ct, hn)
+	m.SetMessageIDWithValue(mid)
+}
+
+// SetMessageIDWithValue sets the message id for the mail
+func (m *Msg) SetMessageIDWithValue(v string) {
+	m.SetHeader(HeaderMessageID, v)
+}
+
+// SetBulk sets the "Precedense: bulk" header which is recommended for
+// automated mails like OOO replies
+// See: https://www.rfc-editor.org/rfc/rfc2076#section-3.9
+func (m *Msg) SetBulk() {
+	m.SetHeader(HeaderPrecedence, "bulk")
+}
+
+// Header FixMe
+func (m *Msg) Header() {
+	fmt.Printf("%+v\n", m.header)
+
+}