Greylisting is a new weapon to use against spam in this great war being waged upon it. With this new shielding method, by which you may block out huge amounts of spam, you are sure to please your email clients!
In name, as well as operation, greylisting is related to whitelisting and blacklisting. What happen is that each time a given mailbox receives an email from an unknown contact (ip), that mail is rejected with a "try again later"-message (This happens at the SMTP layer and is transparent to the end user). This, in the short run, means that all mail gets delayed at least until the sender tries again - but this is where spam loses out! Most spam is not sent out using RFC compliant MTAs; the spamming software will not try again later.
Yes they do. But that does not really make greylisting useless. This delay in new sender contacts also gives you a lot of extra power. This may be an hour, but in this hour there is a large chance that the mass mailer/spammer has been identified by the more conventional anti-spam software. Thus, when he retries it, is likely that we will know him for what he really is!
This siteLearn more about greylisting in our articles section. Check up on other peoples implementations for inspiration/source of your own implementation. When doing greylisting one also needs to consider doing some whitelisting. You may also wish to check our links page for more resources. |
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Latest updates
12/27/07 Some implementations updated and added, articles section re-organised a bit and
a new major user added. |
Forum updates
"MS Exchange 2003 SP2 bug related to greylisting" had a reply added by Hank Freid at May 10 2008 |
