Removed the Bcc header field when sending emails

This way of handling Bcc field is described in RFC 5322 section 3.6.3:
https://tools.ietf.org/html/rfc5322#section-3.6.3

It makes the code much more simple and efficient.

message_test.go

@@ -38,7 +38,7 @@ func TestMessage(t *testing.T) {
 	})
 	msg.SetBody("text/plain", "¡Hola, señor!")
 
-	want := message{
+	want := &message{
 		from: "from@example.com",
 		to: []string{
 			"to@example.com",
@@ -69,7 +69,7 @@ func TestBodyWriter(t *testing.T) {
 	w := msg.GetBodyWriter("text/plain")
 	w.Write([]byte("Test message"))
 
-	want := message{
+	want := &message{
 		from: "from@example.com",
 		to:   []string{"to@example.com"},
 		content: "From: from@example.com\r\n" +
@@ -92,7 +92,7 @@ func TestCustomMessage(t *testing.T) {
 	})
 	msg.SetBody("text/html", "¡Hola, señor!")
 
-	want := message{
+	want := &message{
 		from: "from@example.com",
 		to:   []string{"to@example.com"},
 		content: "From: from@example.com\r\n" +
@@ -116,7 +116,7 @@ func TestUnencodedMessage(t *testing.T) {
 	})
 	msg.SetBody("text/html", "¡Hola, señor!")
 
-	want := message{
+	want := &message{
 		from: "from@example.com",
 		to:   []string{"to@example.com"},
 		content: "From: from@example.com\r\n" +
@@ -142,9 +142,9 @@ func TestRecipients(t *testing.T) {
 	})
 	msg.SetBody("text/plain", "Test message")
 
-	want := message{
+	want := &message{
 		from: "from@example.com",
-		to:   []string{"to@example.com", "cc@example.com"},
+		to:   []string{"to@example.com", "cc@example.com", "bcc1@example.com", "bcc2@example.com"},
 		content: "From: from@example.com\r\n" +
 			"To: to@example.com\r\n" +
 			"Cc: cc@example.com\r\n" +
@@ -154,34 +154,8 @@ func TestRecipients(t *testing.T) {
 			"\r\n" +
 			"Test message",
 	}
-	wantBcc1 := message{
-		from: "from@example.com",
-		to:   []string{"bcc1@example.com"},
-		content: "From: from@example.com\r\n" +
-			"To: to@example.com\r\n" +
-			"Cc: cc@example.com\r\n" +
-			"Bcc: bcc1@example.com\r\n" +
-			"Subject: Hello!\r\n" +
-			"Content-Type: text/plain; charset=UTF-8\r\n" +
-			"Content-Transfer-Encoding: quoted-printable\r\n" +
-			"\r\n" +
-			"Test message",
-	}
-	wantBcc2 := message{
-		from: "from@example.com",
-		to:   []string{"bcc2@example.com"},
-		content: "From: from@example.com\r\n" +
-			"To: to@example.com\r\n" +
-			"Cc: cc@example.com\r\n" +
-			"Bcc: bcc2@example.com\r\n" +
-			"Subject: Hello!\r\n" +
-			"Content-Type: text/plain; charset=UTF-8\r\n" +
-			"Content-Transfer-Encoding: quoted-printable\r\n" +
-			"\r\n" +
-			"Test message",
-	}
 
-	testMessage(t, msg, 0, want, wantBcc1, wantBcc2)
+	testMessage(t, msg, 0, want)
 }
 
 func TestAlternative(t *testing.T) {
@@ -191,7 +165,7 @@ func TestAlternative(t *testing.T) {
 	msg.SetBody("text/plain", "¡Hola, señor!")
 	msg.AddAlternative("text/html", "¡<b>Hola</b>, <i>señor</i>!</h1>")
 
-	want := message{
+	want := &message{
 		from: "from@example.com",
 		to:   []string{"to@example.com"},
 		content: "From: from@example.com\r\n" +
@@ -228,7 +202,7 @@ func TestAttachmentOnly(t *testing.T) {
 	}
 	msg.Attach(f)
 
-	want := message{
+	want := &message{
 		from: "from@example.com",
 		to:   []string{"to@example.com"},
 		content: "From: from@example.com\r\n" +
@@ -250,7 +224,7 @@ func TestAttachment(t *testing.T) {
 	msg.SetBody("text/plain", "Test")
 	msg.Attach(CreateFile("test.pdf", []byte("Content")))
 
-	want := message{
+	want := &message{
 		from: "from@example.com",
 		to:   []string{"to@example.com"},
 		content: "From: from@example.com\r\n" +
@@ -281,7 +255,7 @@ func TestAttachmentsOnly(t *testing.T) {
 	msg.Attach(CreateFile("test.pdf", []byte("Content 1")))
 	msg.Attach(CreateFile("test.zip", []byte("Content 2")))
 
-	want := message{
+	want := &message{
 		from: "from@example.com",
 		to:   []string{"to@example.com"},
 		content: "From: from@example.com\r\n" +
@@ -314,7 +288,7 @@ func TestAttachments(t *testing.T) {
 	msg.Attach(CreateFile("test.pdf", []byte("Content 1")))
 	msg.Attach(CreateFile("test.zip", []byte("Content 2")))
 
-	want := message{
+	want := &message{
 		from: "from@example.com",
 		to:   []string{"to@example.com"},
 		content: "From: from@example.com\r\n" +
@@ -354,7 +328,7 @@ func TestEmbedded(t *testing.T) {
 	msg.Embed(CreateFile("image2.jpg", []byte("Content 2")))
 	msg.SetBody("text/plain", "Test")
 
-	want := message{
+	want := &message{
 		from: "from@example.com",
 		to:   []string{"to@example.com"},
 		content: "From: from@example.com\r\n" +
@@ -395,7 +369,7 @@ func TestFullMessage(t *testing.T) {
 	msg.Attach(CreateFile("test.pdf", []byte("Content 1")))
 	msg.Embed(CreateFile("image.jpg", []byte("Content 2")))
 
-	want := message{
+	want := &message{
 		from: "from@example.com",
 		to:   []string{"to@example.com"},
 		content: "From: from@example.com\r\n" +
@@ -454,7 +428,7 @@ func TestQpLineLength(t *testing.T) {
 			strings.Repeat("0", 75)+"\r\n"+
 			strings.Repeat("0", 76)+"\n")
 
-	want := message{
+	want := &message{
 		from: "from@example.com",
 		to:   []string{"to@example.com"},
 		content: "From: from@example.com\r\n" +
@@ -480,7 +454,7 @@ func TestBase64LineLength(t *testing.T) {
 	msg.SetHeader("To", "to@example.com")
 	msg.SetBody("text/plain", strings.Repeat("0", 58))
 
-	want := message{
+	want := &message{
 		from: "from@example.com",
 		to:   []string{"to@example.com"},
 		content: "From: from@example.com\r\n" +
@@ -494,21 +468,15 @@ func TestBase64LineLength(t *testing.T) {
 	testMessage(t, msg, 0, want)
 }
 
-func testMessage(t *testing.T, msg *Message, bCount int, emails ...message) {
+func testMessage(t *testing.T, msg *Message, bCount int, want *message) {
-	err := Send(stubSendMail(t, bCount, emails...), msg)
+	err := Send(stubSendMail(t, bCount, want), msg)
 	if err != nil {
 		t.Error(err)
 	}
 }
 
-func stubSendMail(t *testing.T, bCount int, emails ...message) SendFunc {
+func stubSendMail(t *testing.T, bCount int, want *message) SendFunc {
-	i := 0
 	return func(from string, to []string, msg io.Reader) error {
-		if i > len(emails) {
-			t.Fatalf("Only %d mails should be sent", len(emails))
-		}
-		want := emails[i]
-
 		if from != want.from {
 			t.Fatalf("Invalid from, got %q, want %q", from, want.from)
 		}
@@ -541,7 +509,6 @@ func stubSendMail(t *testing.T, bCount int, emails ...message) SendFunc {
 				wantMsg = strings.Replace(wantMsg, "_BOUNDARY_"+strconv.Itoa(i+1)+"_", b, -1)
 			}
 		}
-		i++
 
 		compareBodies(t, got, wantMsg)
 

send.go

@@ -52,34 +52,26 @@ func send(s Sender, msg *Message) error {
 	if err != nil {
 		return err
 	}
-	recipients, bcc, err := getRecipients(message)
+	to, err := getRecipients(message)
 	if err != nil {
 		return err
 	}
 
-	h := flattenHeader(message, "")
+	h := flattenHeader(message)
 	body, err := ioutil.ReadAll(message.Body)
 	if err != nil {
 		return err
 	}
 
 	mail := bytes.NewReader(append(h, body...))
-	if err := s.Send(from, recipients, mail); err != nil {
+	if err := s.Send(from, to, mail); err != nil {
 		return err
 	}
 
-	for _, to := range bcc {
-		h = flattenHeader(message, to)
-		mail = bytes.NewReader(append(h, body...))
-		if err := s.Send(from, []string{to}, mail); err != nil {
-			return err
-		}
-	}
-
 	return nil
 }
 
-func flattenHeader(msg *mail.Message, bcc string) []byte {
+func flattenHeader(msg *mail.Message) []byte {
 	buf := getBuffer()
 	defer putBuffer(buf)
 
@@ -89,15 +81,6 @@ func flattenHeader(msg *mail.Message, bcc string) []byte {
 			buf.WriteString(": ")
 			buf.WriteString(strings.Join(value, ", "))
 			buf.WriteString("\r\n")
-		} else if bcc != "" {
-			for _, to := range value {
-				if strings.Contains(to, bcc) {
-					buf.WriteString(field)
-					buf.WriteString(": ")
-					buf.WriteString(to)
-					buf.WriteString("\r\n")
-				}
-			}
 		}
 	}
 	buf.WriteString("\r\n")
@@ -117,38 +100,31 @@ func getFrom(msg *mail.Message) (string, error) {
 	return parseAddress(from)
 }
 
-func getRecipients(msg *mail.Message) (recipients, bcc []string, err error) {
+func getRecipients(msg *mail.Message) ([]string, error) {
-	for _, field := range []string{"Bcc", "To", "Cc"} {
+	var list []string
+	for _, field := range []string{"To", "Cc", "Bcc"} {
 		if addresses, ok := msg.Header[field]; ok {
-			for _, addr := range addresses {
+			for _, a := range addresses {
-				switch field {
+				addr, err := parseAddress(a)
-				case "Bcc":
-					bcc, err = addAdress(bcc, addr)
-				default:
-					recipients, err = addAdress(recipients, addr)
-				}
 				if err != nil {
-					return recipients, bcc, err
+					return nil, err
 				}
+				list = addAdress(list, addr)
 			}
 		}
 	}
 
-	return recipients, bcc, nil
-}
-
-func addAdress(list []string, addr string) ([]string, error) {
-	addr, err := parseAddress(addr)
-	if err != nil {
-		return list, err
-	}
-	for _, a := range list {
-		if addr == a {
 	return list, nil
 }
+
+func addAdress(list []string, addr string) []string {
+	for _, a := range list {
+		if addr == a {
+			return list
+		}
 	}
 
-	return append(list, addr), nil
+	return append(list, addr)
 }
 
 func parseAddress(field string) (string, error) {