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Greylisting
What if my email was rejected and greylisting was mentioned as the cause?
This can happen for various reasons:
- The MTA (mail transfer agent) / email ISP that you use to send email
is not RFC 821 compliant. Contact your ISP.
- The MTA is in some way misconfigured to not automatically retry email messages
that gets rejected with the "try later"-message. Maybe it's timing is off and it retries immediately (which it shouldn't).
Contact your ISP.
- The recipient email server has got greylisting misconfigured, ie. an implementation that just doesn't
let mails through even on later retries. Or maybe their error message is actually wrong: greylisting was NOT
the reason your mail bounced - but something else.
Can you remove me from your blacklist/greylist?
greylisting.org is JUST an information website. We are not responsible for
maintaining any specific blacklists/greylists or for maintaining any whitelists.
You need to contact the actual operator of the mail server that rejecter your
email and find out it was rejected (maybe they offer a whitelisting feature).
What's with all these "lists"? What's the difference?
What is greylisting?
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.
But.. spammers adapt!?
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 site
Learn 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
11/15/09 Added more implementations, articles and more!
05/08/09 Corrected some links, typos and added a bit around the site.
05/18/08 Added some new implementations.
12/27/07 Some implementations updated and added, articles section re-organised a bit and
a new major user added.
08/24/07 Minor design change, new implementations and updated the
problem MTAs section.
05/26/07 Added a section for problem servers/MTA (mail transfer agents) as
well as many more implementations.
02/02/07 Added a new implementation and also an article on
limiting your spam
to the articles page, in which greylisting.org is also featured on page 4 :-)
01/29/07 Integrated forum updates into the homepage (here).
01/26/07 Due to several requests (and in general an increasing amount of traffic), I
have relaunched the forum (NOT phpbb!).
01/25/07 Added the option to toggle older news on/off.
01/23/07 Added another implementation, fixed a link on the exchange implementations page.
01/13/07 Several implementations added and more major users.
10/06/06 A few minor design adjustments.
09/25/06 Some implmentations added and a new link..
08/02/06 Whitelisting page updated, added a new implementation and fixed a link error.
02/28/06 Made a few minor updates.
02/21/06 Some additional implementations added.
01/14/06 Added a link to the links page and updated a few other pages. More to arrive soon!
12/04/05 Added links and implementations and corrected some typos..
08/07/05 Added forums for discussing greylisting, also numerous minor additions.
06/14/05 Few additions in the implementations section.
04/20/05 Long time with no updates, added various links and corrections today.
01/11/05 Fixed various minor issues.
01/02/05 Started moving the site to another server.
12/22/04 Uploaded a new logo (by Ivan)
12/21/04 Anti-Spam Website Greylisting.org Rewarded with Ownership of the Domain from OpenDomain.org
12/19/04 New design comming online
12/17/04 Updated the articles section, design updates
12/15/04 Added another generic greylisting solution.
11/19/04 Updated whitelisting page and postfix implementations page.
10/13/04 Some new implementaions and other minor updates
09/15/04 Added a few implementations and whitelisting entries
08/28/04 Added some major users, made some minor corrections
07/30/04 Much delayed update! (sorry!)
06/03/04 New design online :-)
05/27/04 Added Michael Moritzs' gps for postfix.
05/23/04 Revised and added some stuff on the implementations page
05/15/04 Some spelling errors corrected, added yet another exim greylisting implementation
04/19/04 Site went online.
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