Added a new encoding: Unencoded

export.go

@@ -29,11 +29,7 @@ func (msg *Message) Export() *mail.Message {
 	for _, part := range msg.parts {
 		h := make(map[string][]string)
 		h["Content-Type"] = []string{part.contentType + "; charset=" + msg.charset}
-		if msg.encoding == Base64 {
-			h["Content-Transfer-Encoding"] = []string{string(Base64)}
-		} else {
-			h["Content-Transfer-Encoding"] = []string{string(QuotedPrintable)}
-		}
+		h["Content-Transfer-Encoding"] = []string{string(msg.encoding)}
 
 		w.write(h, part.body.Bytes(), msg.encoding)
 	}
@@ -166,6 +162,8 @@ func (w *messageWriter) writeBody(body []byte, enc Encoding) {
 		writer := base64.NewEncoder(base64.StdEncoding, newBase64LineWriter(subWriter))
 		writer.Write(body)
 		writer.Close()
+	} else if enc == Unencoded {
+		subWriter.Write(body)
 	} else {
 		writer := quotedprintable.NewEncoder(newQpLineWriter(subWriter))
 		writer.Write(body)

gomail.go

@@ -95,6 +95,9 @@ const (
 	QuotedPrintable Encoding = "quoted-printable"
 	// Base64 represents the base64 encoding as defined in RFC 2045.
 	Base64 Encoding = "base64"
+	// Unencoded can be used to avoid encoding the body of an email. The headers
+	// will still be encoded using quoted-printable encoding.
+	Unencoded Encoding = "8bit"
 )
 
 // SetHeader sets a value to the given header field.

gomail_test.go

@@ -95,6 +95,30 @@ func TestCustomMessage(t *testing.T) {
 	testMessage(t, msg, 0, want)
 }
 
+func TestUnencodedMessage(t *testing.T) {
+	msg := NewMessage(SetEncoding(Unencoded))
+	msg.SetHeaders(map[string][]string{
+		"From":    {"from@example.com"},
+		"To":      {"to@example.com"},
+		"Subject": {"Café"},
+	})
+	msg.SetBody("text/html", "¡Hola, señor!")
+
+	want := message{
+		from: "from@example.com",
+		to:   []string{"to@example.com"},
+		content: "From: from@example.com\r\n" +
+			"To: to@example.com\r\n" +
+			"Subject: =?UTF-8?Q?Caf=C3=A9?=\r\n" +
+			"Content-Type: text/html; charset=UTF-8\r\n" +
+			"Content-Transfer-Encoding: 8bit\r\n" +
+			"\r\n" +
+			"¡Hola, señor!",
+	}
+
+	testMessage(t, msg, 0, want)
+}
+
 func TestRecipients(t *testing.T) {
 	msg := NewMessage()
 	msg.SetHeaders(map[string][]string{