.github/workflows/codecov.yml

@@ -33,7 +33,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        go: [1.18, 1.19, '1.20', '1.21', '1.22']
+        go: [1.17, 1.18, 1.19, '1.20', '1.21']
     steps:
     - name: Checkout Code
       uses: actions/checkout@master
@@ -42,14 +42,14 @@ jobs:
       with:
         go-version: ${{ matrix.go }}
     - name: Install sendmail
-      if: matrix.go == '1.22' && matrix.os == 'ubuntu-latest'
+      if: matrix.go == '1.21' && 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 == '1.21' && matrix.os == 'ubuntu-latest'
       uses: codecov/codecov-action@v3
       with:
         token: ${{ secrets.CODECOV_TOKEN }} # not required for public repos

.github/workflows/golangci-lint.yml

@@ -21,7 +21,7 @@ jobs:
     steps:
       - uses: actions/setup-go@v3
         with:
-          go-version: '1.22'
+          go-version: '1.21'
       - uses: actions/checkout@v3
       - name: golangci-lint
         uses: golangci/golangci-lint-action@v3

.github/workflows/sonarqube.yml

@@ -29,7 +29,7 @@ jobs:
       - name: Setup Go
         uses: actions/setup-go@v3
         with:
-          go-version: '1.22.x'
+          go-version: '1.21.x'
           
       - name: Run unit Tests
         run: |

eml.go

@@ -178,6 +178,9 @@ func parseEMLHeaders(mh *nm.Header, m *Msg) error {
 	for _, h := range commonHeaders {
 		if v := mh.Get(h.String()); v != "" {
 			m.SetGenHeader(h, v)
+			if strings.EqualFold(h.String(), "subject") {
+				fmt.Printf("SUBJECT: %s\n", m.GetGenHeader(HeaderSubject)[0])
+			}
 		}
 	}
 
@@ -201,8 +204,7 @@ func parseEMLBodyParts(pm *nm.Message, bodybuf *bytes.Buffer, m *Msg) error {
 		if err := parseEMLBodyPlain(mediatype, pm, bodybuf, m); err != nil {
 			return fmt.Errorf("failed to parse plain body: %w", err)
 		}
-	case strings.EqualFold(mediatype, TypeMultipartAlternative.String()),
-		strings.EqualFold(mediatype, "multipart/mixed"):
+	case strings.EqualFold(mediatype, TypeMultipartAlternative.String()):
 		if err := parseEMLMultipartAlternative(params, bodybuf, m); err != nil {
 			return fmt.Errorf("failed to parse multipart/alternative body: %w", err)
 		}
@@ -264,27 +266,19 @@ func parseEMLMultipartAlternative(params map[string]string, bodybuf *bytes.Buffe
 		if !ok {
 			return fmt.Errorf("failed to get content-type from part")
 		}
-		conType, charSet := parseContentType(mpContentType[0])
-		p := m.newPart(ContentType(conType))
-		p.SetCharset(Charset(charSet))
+		mpContentTypeSplit := strings.Split(mpContentType[0], "; ")
+		p := m.newPart(ContentType(mpContentTypeSplit[0]))
+		parseEMLMultiPartCharset(mpContentTypeSplit, p)
 
 		mpTransferEnc, ok := mpart.Header[HeaderContentTransferEnc.String()]
 		if !ok {
-			// If CTE is empty we can assume that it's a quoted-printable CTE since the
-			// GO stdlib multipart packages deletes that header
-			// See: https://cs.opensource.google/go/go/+/refs/tags/go1.22.0:src/mime/multipart/multipart.go;l=161
-			mpTransferEnc = []string{EncodingQP.String()}
+			return fmt.Errorf("failed to get content-transfer-encoding from part")
 		}
-
 		switch {
 		case strings.EqualFold(mpTransferEnc[0], EncodingB64.String()):
 			if err := handleEMLMultiPartBase64Encoding(mpdata, p); err != nil {
 				return fmt.Errorf("failed to handle multipart base64 transfer-encoding: %w", err)
 			}
-		case strings.EqualFold(mpTransferEnc[0], EncodingQP.String()):
-			p.SetContent(string(mpdata))
-		default:
-			return fmt.Errorf("unsupported Content-Transfer-Encoding")
 		}
 
 		m.parts = append(m.parts, p)
@@ -297,6 +291,17 @@ func parseEMLMultipartAlternative(params map[string]string, bodybuf *bytes.Buffe
 	return nil
 }
 
+// parseEMLMultiPartCharset parses the Charset from a ContentType header and assigns it to a Part
+// TODO: This might be redundant to parseContentType
+func parseEMLMultiPartCharset(mpContentTypeSplit []string, p *Part) {
+	if len(mpContentTypeSplit) > 1 && strings.HasPrefix(strings.ToLower(mpContentTypeSplit[1]), "charset=") {
+		valSplit := strings.Split(mpContentTypeSplit[1], "=")
+		if len(valSplit) > 1 {
+			p.SetCharset(Charset(valSplit[1]))
+		}
+	}
+}
+
 // handleEMLMultiPartBase64Encoding sets the content body of a base64 encoded Part
 func handleEMLMultiPartBase64Encoding(mpdata []byte, p *Part) error {
 	p.SetEncoding(EncodingB64)

encoding.go

@@ -140,8 +140,6 @@ const (
 const (
 	TypeAppOctetStream       ContentType = "application/octet-stream"
 	TypeMultipartAlternative ContentType = "multipart/alternative"
-	TypeMultipartMixed       ContentType = "multipart/mixed"
-	TypeMultipartRelated     ContentType = "multipart/related"
 	TypePGPSignature         ContentType = "application/pgp-signature"
 	TypePGPEncrypted         ContentType = "application/pgp-encrypted"
 	TypeTextHTML             ContentType = "text/html"

encoding_test.go

@@ -40,18 +40,6 @@ func TestContentType_String(t *testing.T) {
 			"ContentType: application/octet-stream", TypeAppOctetStream,
 			"application/octet-stream",
 		},
-		{
-			"ContentType: multipart/alternative", TypeMultipartAlternative,
-			"multipart/alternative",
-		},
-		{
-			"ContentType: multipart/mixed", TypeMultipartMixed,
-			"multipart/mixed",
-		},
-		{
-			"ContentType: multipart/related", TypeMultipartRelated,
-			"multipart/related",
-		},
 		{
 			"ContentType: application/pgp-signature", TypePGPSignature,
 			"application/pgp-signature",

msgwriter.go

@@ -89,11 +89,11 @@ func (mw *msgWriter) writeMsg(m *Msg) {
 	}
 
 	if m.hasMixed() {
-		mw.startMP(MIMEMixed, m.boundary)
+		mw.startMP("mixed", m.boundary)
 		mw.writeString(DoubleNewLine)
 	}
 	if m.hasRelated() {
-		mw.startMP(MIMERelated, m.boundary)
+		mw.startMP("related", m.boundary)
 		mw.writeString(DoubleNewLine)
 	}
 	if m.hasAlt() {