Hi all, wondering if anyone else has or had this issue. Can't seem to find much on how one would solve this. I recently installed the ispconfig plugins for RoundCube. (set them up easily enough). I sent a test message to the email address with the enabled out of office reply. The server sent a message back, however, it stops short of getting all the way to the original sender. The mail server blocks the return reply with the notice below: to=<[email protected]>, relay=spamfilter.email.com[126.96.36.199]:587, delay=1.6, delays=0.28/0.02/1.3/0.07, dsn=5.0.0, status=bounced (host spamfilter.email.com[188.8.131.52] said: 550 Empty envelope senders not allowed (in reply to DATA command)) Jan 2 21:17:09 ns1 postfix/qmgr: DA3B868C0795: removed I can only assume that Roundcube is not attaching a sender email address when responding with the notice. Does anyone know what I can do to make Roundcube include that information in the return reply? Thank you so much in advance! Best regards, and happy new years everyone!!