#145: Support for quoted-printable encoding in email parser

Added support for quoted-printable encoding in email parser to increase its functionality. The change includes a case handling feature for 'EncodingQP' and related conversions to allow for proper message body reading and encoding setting. This improves the robustness and the scope of email content types that the parser can handle."

eml.go

@@ -9,6 +9,7 @@ import (
 	"errors"
 	"fmt"
 	"mime"
+	"mime/quotedprintable"
 	nm "net/mail"
 	"os"
 	"strings"
@@ -132,16 +133,24 @@ func parseEMLBodyParts(pm *nm.Message, mbbuf *bytes.Buffer, m *Msg) error {
 		m.SetCharset(Charset(v))
 	}
 
-	if cte := pm.Header.Get(HeaderContentTransferEnc.String()); cte != "" {
+	cte := pm.Header.Get(HeaderContentTransferEnc.String())
-		switch strings.ToLower(cte) {
-		case NoEncoding.String():
-			m.SetEncoding(NoEncoding)
-		}
-	}
-
 	switch strings.ToLower(mt) {
 	case TypeTextPlain.String():
+		if cte == NoEncoding.String() {
+			m.SetEncoding(NoEncoding)
 			m.SetBodyString(TypeTextPlain, mbbuf.String())
+			break
+		}
+		if cte == EncodingQP.String() {
+			m.SetEncoding(EncodingQP)
+			qpr := quotedprintable.NewReader(mbbuf)
+			qpbuf := bytes.Buffer{}
+			if _, err := qpbuf.ReadFrom(qpr); err != nil {
+				return fmt.Errorf("failed to read quoted-printable body: %w", err)
+			}
+			m.SetBodyString(TypeTextPlain, qpbuf.String())
+			break
+		}
 	default:
 	}
 	return nil