Postfix and Postgrey: a proactive approach to spam filtering

Wednesday, 29 November 2006, 11:05 AM EST

Greylisting is a great way for fighting spams, the basic idea out of it is that spammers mail servers are not respecting RFC standards specifications which basically says that when an email could not be delivered, the mail server should try again later on. By sending so many emails, spammers can't afford to spend to much resources on resending emails when they could not be delivered, so if the email could not be delivered in the first place, they won't send it back to you.

From this ideas, greylisting simply reject any untrusted mail domain by giving a 450 response code, which means "I can't deal with your request now, please try again later". As spam mail server are not usually RFC compliant, they won't try back and therefore you won't get the spam.

At Debuntu.

[ Read more ]




Spotlight

Patching: The least understood line of defense

Posted on 29 August 2014.  |  How many end users, indeed how many IT pros, truly get patching? Sure, many of us see Windows install updates when we shut down our PC and think all is well. Itís not.


Weekly newsletter

Reading our newsletter every Monday will keep you up-to-date with security news.
  



Daily digest

Receive a daily digest of the latest security news.
  

DON'T
MISS

Tue, Sep 2nd
    COPYRIGHT 1998-2014 BY HELP NET SECURITY.   // READ OUR PRIVACY POLICY // ABOUT US // ADVERTISE //