System: Debian perfect setup with ISPConfig. In /etc/postfix/main.cf I have: mailbox_size_limit = 0 set. However, I still seem to have a message size limit imposed on SMTP. When I try to send myself a message with a ~40MB attachment logging directly into my SMTP server, the log tells me: Nov 19 20:57:20 hostname postfix/smtpd: NOQUEUE: reject: MAIL from unknown[18.104.22.168]: 552 Message size exceeds fixed limit; proto=ESMTP helo=<myhost.mydomain.org> Can anyone whack me with a clue-bat and explain what's happening? TIA. Footnotes: 1. Yeah, I know what FTP's for. This was a test.