fix(GODT-2170): Use draft attribute rather than mailbox name

internal/state/mailbox.go

@@ -147,8 +147,14 @@ func (m *Mailbox) GetMessagesWithoutFlagCount(flag string) int {
 
 func (m *Mailbox) AppendRegular(ctx context.Context, literal []byte, flags imap.FlagSet, date time.Time) (imap.UID, error) {
 	var appendIntoDrafts bool
+
+	attr, err := m.Attributes(ctx)
+	if err != nil {
+		return 0, err
+	}
+
 	// Force create message when appending to drafts so that IMAP clients can create new draft messages.
-	if !strings.EqualFold(m.name, "Drafts") {
+	if !attr.Contains(imap.AttrDrafts) {
 		internalIDString, err := rfc822.GetHeaderValue(literal, ids.InternalIDKey)
 		if err != nil {
 			return 0, err

tests/draft_test.go

@@ -1,6 +1,7 @@
 package tests
 
 import (
+	"github.com/ProtonMail/gluon/imap"
 	"regexp"
 	"testing"
 	"time"
@@ -47,7 +48,7 @@ func TestDraftSavedAgain(t *testing.T) {
 	// Email client can save same message i.e.: it will delete old draft
 	// and append one with same content.
 	runOneToOneTestWithAuth(t, defaultServerOptions(t), func(c *testConnection, s *testSession) {
-		mailboxID := s.mailboxCreated("user", []string{"Drafts"})
+		mailboxID := s.mailboxCreatedWithAttributes("user", []string{"Drafts"}, imap.NewFlagSet(imap.AttrDrafts))
 
 		c.C("A002 SELECT Drafts").OK("A002")