Having a bit of a nightmare with our Linux server.
Somehack is using our server for spaming. I sanitaized all inputs, have captcha image, change passwords, etc. but still.
Somehow they keep on doing it. Getting thousands of email by the hour. We have a 3000 emails limit daily, so this is blocking our SMTP nearly right after I clean the queue. The things is that all those emails that keep coming in, are stored as "unprocessed" somewhere and this increase our disk space to the limit and then I cant even see the websites. Our server is a typical Linux, using Plesk 9.3 as panel. On all those spam email, they display email@example.com as the sender, which is a default system address I guess.
I desperately need to stop this and I simply don't know how. Is there a way of blocking that email address from sending emails? Via SSH or in Plesk?
This is the header of 1 of those spam emails:
Received: (qmail 20441 invoked by uid 48); 9 Mar 2012 09:29:55 -0200 Date: 9 Mar 2012 09:29:55 -0200 Message-ID: <firstname.lastname@example.org> To: email@example.com Subject: Viaqra 0,89 From: "Reuben Velasquez" <firstname.lastname@example.org> MIME-Version: 1.0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable