maildir save: Detect when trying to use duplicate GUIDs (filenames) and rename them.
maildir save: Detect when trying to use duplicate GUIDs (filenames) and rename them.

LTD-Beget/dovecot,LTD-Beget/dovecot,LTD-Beget/dovecot,LTD-Beget/dovecot,LTD-Beget/dovecot