fts: Don't crash if application/octet-stream attachment doesn't have filename.
fts: Don't crash if application/octet-stream attachment doesn't have filename.

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