Fix appending to Sent

internal/imap/mailbox_message.go

@@ -126,10 +126,6 @@ func (im *imapMailbox) CreateMessage(flags []string, date time.Time, body imap.L
 
 			// We didn't find the message in the store, so we are currently sending it.
 			logEntry.WithField("time", date).Info("No matching UID, continuing APPEND to Sent")
-
-			// For now we don't import user's own messages to Sent because GetUIDByHeader is not smart enough.
-			// This will be fixed in GODT-143.
-			return nil
 		}
 
 		// This is an APPEND to the Sent folder, so we will set the sent flag

internal/store/mailbox_ids.go

@@ -219,6 +219,11 @@ func (storeMailbox *Mailbox) GetUIDByHeader(header *mail.Header) (foundUID uint3
 	// in PM message. Message-Id in normal copy/move will be the PM internal ID.
 	messageID := header.Get("Message-Id")
 
+	// There is nothing to find, when no Message-Id given.
+	if messageID == "" {
+		return uint32(0)
+	}
+
 	// The most often situation is that message is APPENDed after it was sent so the
 	// Message-ID will be reflected by ExternalID in API message meta-data.
 	externalID := strings.Trim(messageID, "<> ") // remove '<>' to improve match