As of today, all of a sudden, I've started receiving an awful lot of "fax message" email spam, redirecting me to some get_message.php page on a hacked remote server. Now I'm fairly sure the problem has arisen because the originating email address is one on my server and as I understand it, there's no security preventing an email account on a given domain to send mail to that domain... What surprises me is that it's started all of a sudden - I'm getting an email every minute or so! My postfix / dovecot installation is that of the ISPconfig guide, running Ubuntu 12.0.4 LTS. Everything has been fine since I set it up (and I regularly apply security patches), so curious why this has started all of a sudden. I've done some reading up on SASL, but to be honest, I'm not too sure where to start fixing this. Here's a snippet of my /var/log/mail.log. Code: Nov 25 14:23:37 myserver postfix/smtpd: connect from unknown[184.108.40.206] Nov 25 14:23:40 myserver postfix/smtpd: 29276D2F7: client=unknown[220.127.116.11] Nov 25 14:23:40 myserver postfix/cleanup: 29276D2F7: message-id=<72649513420574469980547@MyFax.com> Nov 25 14:23:40 myserver postfix/qmgr: 29276D2F7: from=<NoRep.c@MyFax.com>, size=999, nrcpt=1 (queue active) Nov 25 14:23:40 myserver dovecot: lda(email@example.com): sieve: msgid=<72649513420574469980547@MyFax.com>: stored mail into mailbox 'INBOX' Nov 25 14:23:40 myserver postfix/pipe: 29276D2F7: to=<firstname.lastname@example.org>, relay=dovecot, delay=0.62, delays=0.57/0.03/0/0.02, dsn=2.0.0, status=sent (delivered via dovecot service) Nov 25 14:23:40 myserver postfix/qmgr: 29276D2F7: removed Nov 25 14:23:40 myserver postfix/smtpd: disconnect from unknown[18.104.22.168] Any idea where to start? Thanks in advance.