Merge branch 'main' into feature/168_improve-error-handling

Update doc.go

.cirrus.yml

@@ -6,9 +6,9 @@ freebsd_task:
   name: FreeBSD
 
   matrix:
-    - name: FreeBSD 13.2
+    - name: FreeBSD 13.3
       freebsd_instance:
-        image_family: freebsd-13-2
+        image_family: freebsd-13-3
     - name: FreeBSD 14.0
       freebsd_instance:
         image_family: freebsd-14-0

.github/workflows/codecov.yml

@@ -36,28 +36,28 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        go: [1.18, 1.19, '1.20', '1.21', '1.22']
+        go: ['1.20', '1.21', '1.22', '1.23']
     steps:
     - name: Harden Runner
-      uses: step-security/harden-runner@17d0e2bd7d51742c71671bd19fa12bdc9d40a3d6 # v2.8.1
+      uses: step-security/harden-runner@5c7944e73c4c2a096b17a9cb74d65b6c2bbafbde # v2.9.1
       with:
         egress-policy: audit
 
     - name: Checkout Code
       uses: actions/checkout@61b9e3751b92087fd0b06925ba6dd6314e06f089 # master
     - name: Setup go
-      uses: actions/setup-go@cdcb36043654635271a94b9a6d1392de5bb323a7 # v5.0.1
+      uses: actions/setup-go@0a12ed9d6a96ab950c8f026ed9f722fe0da7ef32 # v5.0.2
       with:
         go-version: ${{ matrix.go }}
     - name: Install sendmail
-      if: matrix.go == '1.22' && matrix.os == 'ubuntu-latest'
+      if: matrix.go == '1.23' && matrix.os == 'ubuntu-latest'
       run: |
         sudo apt-get -y install sendmail; which sendmail
     - name: Run Tests
       run: |
         go test -v -race --coverprofile=coverage.coverprofile --covermode=atomic ./...
     - name: Upload coverage to Codecov
-      if: success() && matrix.go == '1.22' && matrix.os == 'ubuntu-latest'
+      if: success() && matrix.go == '1.23' && matrix.os == 'ubuntu-latest'
       uses: codecov/codecov-action@e28ff129e5465c2c0dcc6f003fc735cb6ae0c673 # v4.5.0
       with:
         token: ${{ secrets.CODECOV_TOKEN }} # not required for public repos

.github/workflows/codeql-analysis.yml

@@ -45,7 +45,7 @@ jobs:
 
     steps:
     - name: Harden Runner
-      uses: step-security/harden-runner@17d0e2bd7d51742c71671bd19fa12bdc9d40a3d6 # v2.8.1
+      uses: step-security/harden-runner@5c7944e73c4c2a096b17a9cb74d65b6c2bbafbde # v2.9.1
       with:
         egress-policy: audit
 
@@ -54,7 +54,7 @@ jobs:
 
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL
-      uses: github/codeql-action/init@b611370bb5703a7efb587f9d136a52ea24c5c38c # v3.25.11
+      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@b611370bb5703a7efb587f9d136a52ea24c5c38c # v3.25.11
+      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@b611370bb5703a7efb587f9d136a52ea24c5c38c # v3.25.11
+      uses: github/codeql-action/analyze@4dd16135b69a43b6c8efb853346f8437d92d3c93 # v3.26.6

.github/workflows/dependency-review.yml

@@ -21,11 +21,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@17d0e2bd7d51742c71671bd19fa12bdc9d40a3d6 # v2.8.1
+        uses: step-security/harden-runner@5c7944e73c4c2a096b17a9cb74d65b6c2bbafbde # v2.9.1
         with:
           egress-policy: audit
 
       - name: 'Checkout Repository'
         uses: actions/checkout@f43a0e5ff2bd294095638e18286ca9a3d1956744 # v3.6.0
       - name: 'Dependency Review'
-        uses: actions/dependency-review-action@72eb03d02c7872a771aacd928f3123ac62ad6d3a # v4.3.3
+        uses: actions/dependency-review-action@5a2ce3f5b92ee19cbb1541a4984c76d921601d7c # v4.3.4

.github/workflows/golangci-lint.yml

@@ -20,16 +20,16 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@17d0e2bd7d51742c71671bd19fa12bdc9d40a3d6 # v2.8.1
+        uses: step-security/harden-runner@5c7944e73c4c2a096b17a9cb74d65b6c2bbafbde # v2.9.1
         with:
           egress-policy: audit
 
-      - uses: actions/setup-go@cdcb36043654635271a94b9a6d1392de5bb323a7 # v5.0.1
+      - uses: actions/setup-go@0a12ed9d6a96ab950c8f026ed9f722fe0da7ef32 # v5.0.2
         with:
-          go-version: '1.22'
+          go-version: '1.23'
       - uses: actions/checkout@f43a0e5ff2bd294095638e18286ca9a3d1956744 # v3.6.0
       - name: golangci-lint
-        uses: golangci/golangci-lint-action@a4f60bb28d35aeee14e6880718e0c85ff1882e64 # v6.0.1
+        uses: golangci/golangci-lint-action@aaa42aa0628b4ae2578232a66b541047968fac86 # v6.1.0
         with:
           # Optional: version of golangci-lint to use in form of v1.2 or v1.2.3 or `latest` to use the latest version
           version: latest

.github/workflows/govulncheck.yml

@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     steps: 
     - name: Harden Runner
-      uses: step-security/harden-runner@17d0e2bd7d51742c71671bd19fa12bdc9d40a3d6 # v2.8.1
+      uses: step-security/harden-runner@5c7944e73c4c2a096b17a9cb74d65b6c2bbafbde # v2.9.1
       with:
         egress-policy: audit
     - name: Run govulncheck

.github/workflows/reuse.yml

@@ -14,10 +14,10 @@ jobs:
     runs-on: ubuntu-latest
     steps: 
     - name: Harden Runner
-      uses: step-security/harden-runner@17d0e2bd7d51742c71671bd19fa12bdc9d40a3d6 # v2.8.1
+      uses: step-security/harden-runner@5c7944e73c4c2a096b17a9cb74d65b6c2bbafbde # v2.9.1
       with:
         egress-policy: audit
 
     - uses: actions/checkout@ee0669bd1cc54295c223e0bb666b733df41de1c5 # v2.7.0
     - name: REUSE Compliance Check
-      uses: fsfe/reuse-action@a46482ca367aef4454a87620aa37c2be4b2f8106 # v3.0.0
+      uses: fsfe/reuse-action@3ae3c6bdf1257ab19397fab11fd3312144692083 # v4.0.0

.github/workflows/scorecards.yml

@@ -35,7 +35,7 @@ jobs:
 
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@17d0e2bd7d51742c71671bd19fa12bdc9d40a3d6 # v2.8.1
+        uses: step-security/harden-runner@5c7944e73c4c2a096b17a9cb74d65b6c2bbafbde # v2.9.1
         with:
           egress-policy: audit
 
@@ -45,7 +45,7 @@ jobs:
           persist-credentials: false
 
       - name: "Run analysis"
-        uses: ossf/scorecard-action@dc50aa9510b46c811795eb24b2f1ba02a914e534 # v2.3.3
+        uses: ossf/scorecard-action@62b2cac7ed8198b15735ed49ab1e5cf35480ba46 # v2.4.0
         with:
           results_file: results.sarif
           results_format: sarif
@@ -67,7 +67,7 @@ jobs:
       # Upload the results as artifacts (optional). Commenting out will disable uploads of run results in SARIF
       # format to the repository Actions tab.
       - name: "Upload artifact"
-        uses: actions/upload-artifact@65462800fd760344b1a7b4382951275a0abb4808 # v4.3.3
+        uses: actions/upload-artifact@50769540e7f4bd5e21e526ee35c689e35e0d6874 # v4.4.0
         with:
           name: SARIF file
           path: results.sarif
@@ -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@b611370bb5703a7efb587f9d136a52ea24c5c38c # v3.25.11
+        uses: github/codeql-action/upload-sarif@4dd16135b69a43b6c8efb853346f8437d92d3c93 # v3.26.6
         with:
           sarif_file: results.sarif

.github/workflows/sonarqube.yml

@@ -27,7 +27,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@17d0e2bd7d51742c71671bd19fa12bdc9d40a3d6 # v2.8.1
+        uses: step-security/harden-runner@5c7944e73c4c2a096b17a9cb74d65b6c2bbafbde # v2.9.1
         with:
           egress-policy: audit
 
@@ -36,20 +36,20 @@ jobs:
           fetch-depth: 0
           
       - name: Setup Go
-        uses: actions/setup-go@cdcb36043654635271a94b9a6d1392de5bb323a7 # v5.0.1
+        uses: actions/setup-go@0a12ed9d6a96ab950c8f026ed9f722fe0da7ef32 # v5.0.2
         with:
-          go-version: '1.22.x'
+          go-version: '1.23.x'
           
       - name: Run unit Tests
         run: |
           go test -v -race --coverprofile=./cov.out ./...
 
-      - uses: sonarsource/sonarqube-scan-action@540792c588b5c2740ad2bb4667db5cd46ae678f2 # master
+      - uses: sonarsource/sonarqube-scan-action@0c0f3958d90fc466625f1d1af1f47bddd4cc6bd1 # master
         env:
           SONAR_TOKEN: ${{ secrets.SONAR_TOKEN }}
           SONAR_HOST_URL: ${{ secrets.SONAR_HOST_URL }}
           
-      - uses: sonarsource/sonarqube-quality-gate-action@72f24ebf1f81eda168a979ce14b8203273b7c3ad # master
+      - uses: sonarsource/sonarqube-quality-gate-action@dc2f7b0dd95544cd550de3028f89193576e958b9 # master
         timeout-minutes: 5
         env:
           SONAR_TOKEN: ${{ secrets.SONAR_TOKEN }}

.golangci.toml

@@ -3,8 +3,9 @@
 ## SPDX-License-Identifier: MIT
 
 [run]
-go = "1.22"
+go = "1.23"
 tests = true
+exclude-dirs = ["examples"]
 
 [linters]
 enable = ["stylecheck", "whitespace", "containedctx", "contextcheck", "decorder",

b64linebreaker.go

@@ -5,7 +5,7 @@
 package mail
 
 import (
-	"fmt"
+	"errors"
 	"io"
 )
 
@@ -26,7 +26,7 @@ var newlineBytes = []byte(SingleNewLine)
 // line length is reached
 func (l *Base64LineBreaker) Write(data []byte) (numBytes int, err error) {
 	if l.out == nil {
-		err = fmt.Errorf(ErrNoOutWriter)
+		err = errors.New(ErrNoOutWriter)
 		return
 	}
 	if l.used+len(data) < MaxBodyLength {

client.go

@@ -683,7 +683,7 @@ func (c *Client) DialAndSendWithContext(ctx context.Context, messages ...*Msg) e
 		return fmt.Errorf("send failed: %w", err)
 	}
 	if err := c.Close(); err != nil {
-		return fmt.Errorf("failed to close connction: %w", err)
+		return fmt.Errorf("failed to close connection: %w", err)
 	}
 	return nil
 }

doc.go

@@ -6,4 +6,4 @@
 package mail
 
 // VERSION is used in the default user agent string
-const VERSION = "0.4.2"
+const VERSION = "0.4.4"

eml.go

@@ -180,7 +180,15 @@ func parseEMLBodyParts(parsedMsg *netmail.Message, bodybuf *bytes.Buffer, msg *M
 	// Extract the transfer encoding of the body
 	mediatype, params, err := mime.ParseMediaType(parsedMsg.Header.Get(HeaderContentType.String()))
 	if err != nil {
-		return fmt.Errorf("failed to extract content type: %w", err)
+		switch {
+		// If no Content-Type header is found, we assume that this is a plain text, 7bit, US-ASCII mail
+		case strings.EqualFold(err.Error(), "mime: no media type"):
+			mediatype = TypeTextPlain.String()
+			params = make(map[string]string)
+			params["charset"] = CharsetASCII.String()
+		default:
+			return fmt.Errorf("failed to extract content type: %w", err)
+		}
 	}
 	if value, ok := params["charset"]; ok {
 		msg.SetCharset(Charset(value))
@@ -207,6 +215,12 @@ func parseEMLBodyParts(parsedMsg *netmail.Message, bodybuf *bytes.Buffer, msg *M
 // parseEMLBodyPlain parses the mail body of plain type mails
 func parseEMLBodyPlain(mediatype string, parsedMsg *netmail.Message, bodybuf *bytes.Buffer, msg *Msg) error {
 	contentTransferEnc := parsedMsg.Header.Get(HeaderContentTransferEnc.String())
+	// According to RFC2045, if no Content-Transfer-Encoding is set, we can imply 7bit US-ASCII encoding
+	if contentTransferEnc == "" || strings.EqualFold(contentTransferEnc, EncodingUSASCII.String()) {
+		msg.SetEncoding(EncodingUSASCII)
+		msg.SetBodyString(ContentType(mediatype), bodybuf.String())
+		return nil
+	}
 	if strings.EqualFold(contentTransferEnc, NoEncoding.String()) {
 		msg.SetEncoding(NoEncoding)
 		msg.SetBodyString(ContentType(mediatype), bodybuf.String())
@@ -308,14 +322,22 @@ ReadNextPart:
 		}
 
 		switch {
+		case strings.EqualFold(mutliPartTransferEnc[0], EncodingUSASCII.String()):
+			part.SetEncoding(EncodingUSASCII)
+			part.SetContent(string(multiPartData))
+		case strings.EqualFold(mutliPartTransferEnc[0], NoEncoding.String()):
+			part.SetEncoding(NoEncoding)
+			part.SetContent(string(multiPartData))
 		case strings.EqualFold(mutliPartTransferEnc[0], EncodingB64.String()):
-			if err := handleEMLMultiPartBase64Encoding(multiPartData, part); err != nil {
+			part.SetEncoding(EncodingB64)
+			if err = handleEMLMultiPartBase64Encoding(multiPartData, part); err != nil {
 				return fmt.Errorf("failed to handle multipart base64 transfer-encoding: %w", err)
 			}
 		case strings.EqualFold(mutliPartTransferEnc[0], EncodingQP.String()):
+			part.SetEncoding(EncodingQP)
 			part.SetContent(string(multiPartData))
 		default:
-			return fmt.Errorf("unsupported Content-Transfer-Encoding")
+			return fmt.Errorf("unsupported Content-Transfer-Encoding: %s", mutliPartTransferEnc[0])
 		}
 
 		msg.parts = append(msg.parts, part)

eml_test.go

@@ -14,6 +14,16 @@ import (
 )
 
 const (
+	// RFC 5322 example mail
+	// See: https://datatracker.ietf.org/doc/html/rfc5322#appendix-A.1.1
+	exampleMailRFC5322A11 = `From: John Doe <jdoe@machine.example>
+To: Mary Smith <mary@example.net>
+Subject: Saying Hello
+Date: Fri, 21 Nov 1997 09:55:06 -0600
+Message-ID: <1234@local.machine.example>
+
+This is a message just to say hello.
+So, "Hello".`
 	exampleMailPlainNoEnc = `Date: Wed, 01 Nov 2023 00:00:00 +0000
 MIME-Version: 1.0
 Message-ID: <1305604950.683004066175.AAAAAAAAaaaaaaaaB@go-mail.dev>
@@ -32,6 +42,29 @@ This is a test mail. Please do not reply to this. Also this line is very long so
 should be wrapped.
 
 
+Thank your for your business!
+The go-mail team
+
+--
+This is a signature`
+	exampleMailPlain7Bit = `Date: Wed, 01 Nov 2023 00:00:00 +0000
+MIME-Version: 1.0
+Message-ID: <1305604950.683004066175.AAAAAAAAaaaaaaaaB@go-mail.dev>
+Subject: Example mail // plain text without encoding
+User-Agent: go-mail v0.4.0 // https://github.com/wneessen/go-mail
+X-Mailer: go-mail v0.4.0 // https://github.com/wneessen/go-mail
+From: "Toni Tester" <go-mail@go-mail.dev>
+To: <go-mail+test@go-mail.dev>
+Cc: <go-mail+cc@go-mail.dev>
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 7bit
+
+Dear Customer,
+
+This is a test mail. Please do not reply to this. Also this line is very long so it
+should be wrapped.
+
+
 Thank your for your business!
 The go-mail team
 
@@ -49,18 +82,6 @@ Cc: <go-mail+cc@go-mail.dev>
 Content-Type: text/plain; charset=UTF-8
 Content-Transfer-Encoding: base64
 
-This plain text body should not be parsed as Base64.
-`
-	exampleMailPlainNoContentType = `Date: Wed, 01 Nov 2023 00:00:00 +0000
-MIME-Version: 1.0
-Message-ID: <1305604950.683004066175.AAAAAAAAaaaaaaaaB@go-mail.dev>
-Subject: Example mail // plain text without encoding
-User-Agent: go-mail v0.4.0 // https://github.com/wneessen/go-mail
-X-Mailer: go-mail v0.4.0 // https://github.com/wneessen/go-mail
-From: "Toni Tester" <go-mail@go-mail.dev>
-To: <go-mail+test@go-mail.dev>
-Cc: <go-mail+cc@go-mail.dev>
-
 This plain text body should not be parsed as Base64.
 `
 	exampleMailPlainUnknownContentType = `Date: Wed, 01 Nov 2023 00:00:00 +0000
@@ -525,6 +546,72 @@ hw22iFHl7YlpOmedZvtMTfQffXeXnvI+rTKNxguyvDKvB7U4qQAAAAlwSFlzAAALEwAACxMBAJqc
 GAAAABFJREFUCJljnMoAA0wMNGcCAEQrAKk9oHKhAAAAAElFTkSuQmCC
 
 --fe785e0384e2607697cc2ecb17cce003003bb7ca9112104f3e8ce727edb5--`
+	exampleMultiPart7BitBase64 = `Date: Wed, 01 Nov 2023 00:00:00 +0000
+MIME-Version: 1.0
+Message-ID: <1305604950.683004066175.AAAAAAAAaaaaaaaaB@go-mail.dev>
+Subject: Example mail // 7bit with base64 attachment
+User-Agent: go-mail v0.4.1 // https://github.com/wneessen/go-mail
+X-Mailer: go-mail v0.4.1 // https://github.com/wneessen/go-mail
+From: "Toni Tester" <go-mail@go-mail.dev>
+To: <go-mail+test@go-mail.dev>
+Cc: <go-mail+cc@go-mail.dev>
+Content-Type: multipart/mixed;
+ boundary="------------26A45336F6C6196BD8BBA2A2"
+
+This is a multi-part message in MIME format.
+--------------26A45336F6C6196BD8BBA2A2
+Content-Type: text/plain; charset=US-ASCII; format=flowed
+Content-Transfer-Encoding: 7bit
+
+testtest
+testtest
+testtest
+testtest
+testtest
+testtest
+
+--------------26A45336F6C6196BD8BBA2A2
+Content-Type: text/plain; charset=UTF-8;
+ name="testfile.txt"
+Content-Transfer-Encoding: base64
+Content-Disposition: attachment;
+ filename="testfile.txt"
+
+VGhpcyBpcyBhIHRlc3QgaW4gQmFzZTY0
+--------------26A45336F6C6196BD8BBA2A2--`
+	exampleMultiPart8BitBase64 = `Date: Wed, 01 Nov 2023 00:00:00 +0000
+MIME-Version: 1.0
+Message-ID: <1305604950.683004066175.AAAAAAAAaaaaaaaaB@go-mail.dev>
+Subject: Example mail // 8bit with base64 attachment
+User-Agent: go-mail v0.4.1 // https://github.com/wneessen/go-mail
+X-Mailer: go-mail v0.4.1 // https://github.com/wneessen/go-mail
+From: "Toni Tester" <go-mail@go-mail.dev>
+To: <go-mail+test@go-mail.dev>
+Cc: <go-mail+cc@go-mail.dev>
+Content-Type: multipart/mixed;
+ boundary="------------26A45336F6C6196BD8BBA2A2"
+
+This is a multi-part message in MIME format.
+--------------26A45336F6C6196BD8BBA2A2
+Content-Type: text/plain; charset=US-ASCII; format=flowed
+Content-Transfer-Encoding: 8bit
+
+testtest
+testtest
+testtest
+testtest
+testtest
+testtest
+
+--------------26A45336F6C6196BD8BBA2A2
+Content-Type: text/plain; charset=UTF-8;
+ name="testfile.txt"
+Content-Transfer-Encoding: base64
+Content-Disposition: attachment;
+ filename="testfile.txt"
+
+VGhpcyBpcyBhIHRlc3QgaW4gQmFzZTY0
+--------------26A45336F6C6196BD8BBA2A2--`
 )
 
 func TestEMLToMsgFromString(t *testing.T) {
@@ -534,6 +621,14 @@ func TestEMLToMsgFromString(t *testing.T) {
 		enc  string
 		sub  string
 	}{
+		{
+			"RFC5322 A1.1", exampleMailRFC5322A11, "7bit",
+			"Saying Hello",
+		},
+		{
+			"Plain text no encoding (7bit)", exampleMailPlain7Bit, "7bit",
+			"Example mail // plain text without encoding",
+		},
 		{
 			"Plain text no encoding", exampleMailPlainNoEnc, "8bit",
 			"Example mail // plain text without encoding",
@@ -638,12 +733,6 @@ func TestEMLToMsgFromReaderFailing(t *testing.T) {
 		t.Error("EML from Reader with unknown content type was supposed to fail, but didn't")
 	}
 	mailbuf.Reset()
-	mailbuf.WriteString(exampleMailPlainNoContentType)
-	_, err = EMLToMsgFromReader(mailbuf)
-	if err == nil {
-		t.Error("EML from Reader with no content type was supposed to fail, but didn't")
-	}
-	mailbuf.Reset()
 	mailbuf.WriteString(exampleMailPlainUnsupportedTransferEnc)
 	_, err = EMLToMsgFromReader(mailbuf)
 	if err == nil {
@@ -707,17 +796,6 @@ func TestEMLToMsgFromFileFailing(t *testing.T) {
 	if err = os.RemoveAll(tempDir); err != nil {
 		t.Error("failed to remove temp dir:", err)
 	}
-	tempDir, tempFile, err = stringToTempFile(exampleMailPlainNoContentType, "testmail")
-	if err != nil {
-		t.Errorf("failed to write EML string to temp file: %s", err)
-	}
-	_, err = EMLToMsgFromFile(tempFile)
-	if err == nil {
-		t.Error("EML from Reader with no content type was supposed to fail, but didn't")
-	}
-	if err = os.RemoveAll(tempDir); err != nil {
-		t.Error("failed to remove temp dir:", err)
-	}
 	tempDir, tempFile, err = stringToTempFile(exampleMailPlainUnsupportedTransferEnc, "testmail")
 	if err != nil {
 		t.Errorf("failed to write EML string to temp file: %s", err)
@@ -866,6 +944,58 @@ func TestEMLToMsgFromStringMultipartMixedAlternativeRelated(t *testing.T) {
 	}
 }
 
+func TestEMLToMsgFromStringMultipartMixedWith7Bit(t *testing.T) {
+	wantSubject := "Example mail // 7bit with base64 attachment"
+	msg, err := EMLToMsgFromString(exampleMultiPart7BitBase64)
+	if err != nil {
+		t.Errorf("EML multipart mixed with 7bit: %s", err)
+	}
+	if subject := msg.GetGenHeader(HeaderSubject); len(subject) > 0 && !strings.EqualFold(subject[0], wantSubject) {
+		t.Errorf("EMLToMsgFromString of EML multipart mixed with 7bit: expected subject: %s,"+
+			" but got: %s", wantSubject, subject[0])
+	}
+	if len(msg.parts) != 1 {
+		t.Errorf("EMLToMsgFromString of EML multipart mixed with 7bit failed: expected 1 part, got: %d",
+			len(msg.parts))
+		return
+	}
+	if !strings.EqualFold(msg.parts[0].GetEncoding().String(), EncodingUSASCII.String()) {
+		t.Errorf("EMLToMsgFromString of EML multipart mixed with 7bit failed: expected encoding: %s, got %s",
+			EncodingUSASCII.String(), msg.parts[0].GetEncoding().String())
+	}
+	if len(msg.attachments) != 1 {
+		t.Errorf("EMLToMsgFromString of EML multipart mixed with 7bit failed: expected 1 attachment, got: %d",
+			len(msg.attachments))
+		return
+	}
+}
+
+func TestEMLToMsgFromStringMultipartMixedWith8Bit(t *testing.T) {
+	wantSubject := "Example mail // 8bit with base64 attachment"
+	msg, err := EMLToMsgFromString(exampleMultiPart8BitBase64)
+	if err != nil {
+		t.Errorf("EML multipart mixed with 8bit: %s", err)
+	}
+	if subject := msg.GetGenHeader(HeaderSubject); len(subject) > 0 && !strings.EqualFold(subject[0], wantSubject) {
+		t.Errorf("EMLToMsgFromString of EML multipart mixed with 8bit: expected subject: %s,"+
+			" but got: %s", wantSubject, subject[0])
+	}
+	if len(msg.parts) != 1 {
+		t.Errorf("EMLToMsgFromString of EML multipart mixed with 8bit failed: expected 1 part, got: %d",
+			len(msg.parts))
+		return
+	}
+	if !strings.EqualFold(msg.parts[0].GetEncoding().String(), NoEncoding.String()) {
+		t.Errorf("EMLToMsgFromString of EML multipart mixed with 8bit failed: expected encoding: %s, got %s",
+			NoEncoding.String(), msg.parts[0].GetEncoding().String())
+	}
+	if len(msg.attachments) != 1 {
+		t.Errorf("EMLToMsgFromString of EML multipart mixed with 8bit failed: expected 1 attachment, got: %d",
+			len(msg.attachments))
+		return
+	}
+}
+
 // stringToTempFile is a helper method that will create a temporary file form a give data string
 func stringToTempFile(data, name string) (string, string, error) {
 	tempDir, err := os.MkdirTemp("", fmt.Sprintf("*-%s", name))

encoding.go

@@ -27,6 +27,9 @@ const (
 	// EncodingQP represents the "quoted-printable" encoding as specified in RFC 2045.
 	EncodingQP Encoding = "quoted-printable"
 
+	// EncodingUSASCII represents encoding with only US-ASCII characters (aka 7Bit)
+	EncodingUSASCII Encoding = "7bit"
+
 	// NoEncoding avoids any character encoding (except of the mail headers)
 	NoEncoding Encoding = "8bit"
 )

encoding_test.go

@@ -16,6 +16,7 @@ func TestEncoding_String(t *testing.T) {
 		{"Encoding: Base64", EncodingB64, "base64"},
 		{"Encoding: QP", EncodingQP, "quoted-printable"},
 		{"Encoding: None/8bit", NoEncoding, "8bit"},
+		{"Encoding: US-ASCII/7bit", EncodingUSASCII, "7bit"},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {

msg.go

@@ -684,11 +684,18 @@ func (m *Msg) GetBoundary() string {
 	return m.boundary
 }
 
-// SetAttachements sets the attachements of the message.
+// SetAttachments sets the attachments of the message.
-func (m *Msg) SetAttachements(files []*File) {
+func (m *Msg) SetAttachments(files []*File) {
 	m.attachments = files
 }
 
+// SetAttachements sets the attachments of the message.
+//
+// Deprecated: use SetAttachments instead.
+func (m *Msg) SetAttachements(files []*File) {
+	m.SetAttachments(files)
+}
+
 // UnsetAllAttachments unset the attachments of the message.
 func (m *Msg) UnsetAllAttachments() {
 	m.attachments = nil
@@ -736,7 +743,7 @@ func (m *Msg) SetBodyWriter(
 // The content type will be set to text/html automatically
 func (m *Msg) SetBodyHTMLTemplate(tpl *ht.Template, data interface{}, opts ...PartOption) error {
 	if tpl == nil {
-		return fmt.Errorf(errTplPointerNil)
+		return errors.New(errTplPointerNil)
 	}
 	buffer := bytes.Buffer{}
 	if err := tpl.Execute(&buffer, data); err != nil {
@@ -751,7 +758,7 @@ func (m *Msg) SetBodyHTMLTemplate(tpl *ht.Template, data interface{}, opts ...Pa
 // The content type will be set to text/plain automatically
 func (m *Msg) SetBodyTextTemplate(tpl *tt.Template, data interface{}, opts ...PartOption) error {
 	if tpl == nil {
-		return fmt.Errorf(errTplPointerNil)
+		return errors.New(errTplPointerNil)
 	}
 	buf := bytes.Buffer{}
 	if err := tpl.Execute(&buf, data); err != nil {
@@ -783,7 +790,7 @@ func (m *Msg) AddAlternativeWriter(
 // The content type will be set to text/html automatically
 func (m *Msg) AddAlternativeHTMLTemplate(tpl *ht.Template, data interface{}, opts ...PartOption) error {
 	if tpl == nil {
-		return fmt.Errorf(errTplPointerNil)
+		return errors.New(errTplPointerNil)
 	}
 	buffer := bytes.Buffer{}
 	if err := tpl.Execute(&buffer, data); err != nil {
@@ -798,7 +805,7 @@ func (m *Msg) AddAlternativeHTMLTemplate(tpl *ht.Template, data interface{}, opt
 // The content type will be set to text/plain automatically
 func (m *Msg) AddAlternativeTextTemplate(tpl *tt.Template, data interface{}, opts ...PartOption) error {
 	if tpl == nil {
-		return fmt.Errorf(errTplPointerNil)
+		return errors.New(errTplPointerNil)
 	}
 	buffer := bytes.Buffer{}
 	if err := tpl.Execute(&buffer, data); err != nil {
@@ -1307,7 +1314,7 @@ func fileFromReadSeeker(name string, reader io.ReadSeeker) *File {
 // fileFromHTMLTemplate returns a File pointer form a given html/template.Template
 func fileFromHTMLTemplate(name string, tpl *ht.Template, data interface{}) (*File, error) {
 	if tpl == nil {
-		return nil, fmt.Errorf(errTplPointerNil)
+		return nil, errors.New(errTplPointerNil)
 	}
 	buffer := bytes.Buffer{}
 	if err := tpl.Execute(&buffer, data); err != nil {
@@ -1319,7 +1326,7 @@ func fileFromHTMLTemplate(name string, tpl *ht.Template, data interface{}) (*Fil
 // fileFromTextTemplate returns a File pointer form a given text/template.Template
 func fileFromTextTemplate(name string, tpl *tt.Template, data interface{}) (*File, error) {
 	if tpl == nil {
-		return nil, fmt.Errorf(errTplPointerNil)
+		return nil, errors.New(errTplPointerNil)
 	}
 	buffer := bytes.Buffer{}
 	if err := tpl.Execute(&buffer, data); err != nil {

msg_test.go

@@ -1413,7 +1413,7 @@ func TestMsg_SetAttachments(t *testing.T) {
 			for _, f := range tt.files {
 				files = append(files, &File{Name: f})
 			}
-			m.SetAttachements(files)
+			m.SetAttachments(files)
 			if len(m.attachments) != len(files) {
 				t.Errorf("SetAttachements() failed. Number of attachments expected: %d, got: %d", len(files),
 					len(m.attachments))
@@ -1448,7 +1448,7 @@ func TestMsg_UnsetAllAttachments(t *testing.T) {
 			for _, f := range tt.attachments {
 				files = append(files, &File{Name: f})
 			}
-			m.SetAttachements(files)
+			m.SetAttachments(files)
 
 			if len(m.attachments) != len(files) {
 				t.Errorf("SetAttachements() failed. Number of attachments expected: %d, got: %d", len(files),
@@ -1610,7 +1610,7 @@ func TestMsg_UnsetAllParts(t *testing.T) {
 			for _, f := range tt.attachments {
 				attachments = append(attachments, &File{Name: f})
 			}
-			m.SetAttachements(attachments)
+			m.SetAttachments(attachments)
 			if len(m.attachments) != len(attachments) {
 				t.Errorf("SetAttachements() failed. Number of attachments files expected: %d, got: %d",
 					len(attachments), len(m.attachments))

msgwriter_test.go

@@ -122,7 +122,7 @@ func TestMsgWriter_writeMsg(t *testing.T) {
 			em += fmt.Sprintf("* incorrect %q field", ea[e])
 		}
 		em += fmt.Sprintf("\n\nFull message:\n%s", ms)
-		t.Errorf(em)
+		t.Error(em)
 	}
 }
 

smtp/auth_login.go

@@ -20,13 +20,15 @@ const (
 	// extension.
 	//
 	// See: https://learn.microsoft.com/en-us/openspecs/exchange_server_protocols/ms-xlogin/.
-	LoginXUsernameChallenge = "Username:"
+	LoginXUsernameChallenge      = "Username:"
+	LoginXUsernameLowerChallenge = "username:"
 
 	// LoginXPasswordChallenge represents the Password Challenge response sent by the SMTP server per the AUTH LOGIN
 	// extension.
 	//
 	//	See: https://learn.microsoft.com/en-us/openspecs/exchange_server_protocols/ms-xlogin/.
-	LoginXPasswordChallenge = "Password:"
+	LoginXPasswordChallenge      = "Password:"
+	LoginXPasswordLowerChallenge = "password:"
 
 	// LoginXDraftUsernameChallenge represents the Username Challenge response sent by the SMTP server per the IETF
 	// draft AUTH LOGIN extension. It should be noted this extension is an expired draft which was never formally
@@ -76,9 +78,9 @@ func (a *loginAuth) Start(server *ServerInfo) (string, []byte, error) {
 func (a *loginAuth) Next(fromServer []byte, more bool) ([]byte, error) {
 	if more {
 		switch string(fromServer) {
-		case LoginXUsernameChallenge, LoginXDraftUsernameChallenge:
+		case LoginXUsernameChallenge, LoginXUsernameLowerChallenge, LoginXDraftUsernameChallenge:
 			return []byte(a.username), nil
-		case LoginXPasswordChallenge, LoginXDraftPasswordChallenge:
+		case LoginXPasswordChallenge, LoginXPasswordLowerChallenge, LoginXDraftPasswordChallenge:
 			return []byte(a.password), nil
 		default:
 			return nil, fmt.Errorf("unexpected server response: %s", string(fromServer))