Question regarding inbound filtering on email
I work at a small web dev company that also does email hosting via smartermail. Recently, we've been encountering a problem in which spammers compromise email passwords and subsequently send out massive numbers of emails which results in our servers becoming blacklisted. We are using barracuda networks email security to curb the problem, but it has thus far been ineffective.
Does anyone have an idea of how to prevent this kind of attack?
Posted Sep 20, 2013, 4:48 PM UTC
22
Sounds like you need better passwords... A quick look at Smartermail's site says :
"Ban weak passwords Set and enforce password rules to decrease the likelihood that the security of a user’s mailbox will be breached. Then use the password compliance report to identify accounts that don’t meet the updated password requirements and send them a request to change their passwords."
May want to start there...
Also, Is there any way to 'throttle' the number of emails sent? such as under 100/min? That may be a way to at least curb the issue..
Another thing I did when I admined exchange was I set up RBLs in the firewall before the server, this way I could make sure some addresses never hit the mail server, let the firewall deal with the blocking and the mail server deal with the mail. Not saying that it never needed tweaking but it helped a lot with spam.
Oh, Make sure you are not an open relay too, a quick trip over to http://mxtoolbox.com/ could tell you that much.
I really appreciate the reply. My background is in computer science (and that's primarily what I do there, but was asked to help out) -- I'm certainly no expert with regard to email hosting. We're currently working on moving people over to a new mail server. We're planning to force users to change their passwords afterwards. As for throttling, I'm not sure but will find out.