I have been displeased with the massive upswing in spam, and not looking forward to 30-40k spam messages next month. So I did some research on the additional features of our MTA, and then did some analysis of the spam we had. With a few quick changes, focusing on where/from whom we were getting the most spam, I instituted and tested some additional filter elements.
If you get caught in this filter and need to let me know, contact me through gmail.com. I am there as joe.landman .
I had looked at postgrey, and other things in the past. Even used postgrey and really liked it. Until it bounced emails from customers.
Yeah, this was due to Microsoft’s exchange server, not doing SMTP correctly (go figure). And yes, they could have fixed it. But they didn’t.
So we have to deal with the blowback from their design/implementation issues. Which means we have to be sensitive to those afflicted with Exchange, and make sure the measures we take to block spam do not simply kill off all new mail from people whom have not mailed us recently.
Which is what postgrey does.
So I reviewed incoming spam headers, and how the mail log tracked/id’ed them. And I found a few patterns in the data that the tagger didn’t have built in it. But postfix has support for these patterns.
Implemented them, and testing now. Checking carefully to make sure no real mail is lost.
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