fix: better draft detection for parentID

Changelog.md

@@ -30,6 +30,7 @@ Changelog [format](http://keepachangelog.com/en/1.0.0/)
 
 ### Fixed
 * Use correct binary name when finding location of addcert.scpt
+* Correctly detect if a message is a draft even if does not have DraftLabel
 
 ## [v1.2.6] Donghai - beta (2020-03-31)
 

internal/smtp/user.go

@@ -382,7 +382,7 @@ func (su *smtpUser) handleReferencesHeader(m *pmapi.Message) (draftID, parentID
 				}
 				metadata, _, _ := su.client.ListMessages(filter)
 				for _, m := range metadata {
-					if isDraft(m) {
+					if m.IsDraft() {
 						draftID = m.ID
 					} else {
 						parentID = m.ID
@@ -411,15 +411,6 @@ func (su *smtpUser) handleReferencesHeader(m *pmapi.Message) (draftID, parentID
 	return draftID, parentID
 }
 
-func isDraft(m *pmapi.Message) bool {
-	for _, labelID := range m.LabelIDs {
-		if labelID == pmapi.DraftLabel {
-			return true
-		}
-	}
-	return false
-}
-
 func (su *smtpUser) handleSenderAndRecipients(m *pmapi.Message, addr *pmapi.Address, from string, to []string) (err error) {
 	from = pmapi.ConstructAddress(from, addr.Email)
 

pkg/pmapi/messages.go

@@ -219,6 +219,13 @@ func (m *Message) UnmarshalJSON(b []byte) error {
 	return nil
 }
 
+// IsDraft returns whether the message should be considered to be a draft.
+// A draft is complicated. It might have pmapi.DraftLabel but it might not.
+// The real API definition of IsDraft is that it is neither sent nor received -- we should use that here.
+func (m *Message) IsDraft() bool {
+	return (m.Flags & (FlagReceived | FlagSent)) == 0
+}
+
 func (m *Message) IsBodyEncrypted() bool {
 	trimmedBody := strings.TrimSpace(m.Body)
 	return strings.HasPrefix(trimmedBody, MessageHeader) &&