Angelin Lalev wrote:
Hi List, My e-mail server is running the latest spamassassin with all of the blacklist enabled and etc. but I still receive over 20 spam messages a day ("image" spam mostly). The situation with other users may be worse. That's why I was thinking about some tool that 1. store incoming email 2. send request to the sender of the message, requiring to go to some address and enter the numbers (letters) from image3. if the puzzle is solved in time (week or so) deliver the message, otherwise delete it.Is there such tool(s) ?
I use grey listing and spamhaus xbl, no spamassasin or content analysis. Apart from grey listing and spamhaus, I block in my firewall IP ranges I have found un trustable, particular China and Korea, and ranges assigned dynamically, and I have some header analysis rules.
I get about 2 spam mails a day.The earlier you can reject a message the less resources it takes, see how much you can reject on the envelope rather than data.
I have found that many spammers use my servers name or IP in HELO, so I reject that. Also, reject unresolvable domains etc, simple stuff.
Really, if you want to effectively address the problems, store all spam, create a spambox for users to forward their spam to. Analyse it every now and then. For example I did this to idenfity IP ranges sending spam.
With greylisting, I have found that greylisting 5 minutes will delay mail significantly and some mail will not be delivered. 3 minutes seems better.
Cheers, Erik -- Ph: +34.666334818 web: http://www.locolomo.org
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