Greylisting.Org >

Problem MTAs/email services


In this section you can read about various email services/MTAs (mail transfer agents) that does not function properly with greylisting (ie. it does not, as expected and according to the standards, resend messeges that was greylisted).

Microsoft Exchange 2003 and greylisting

There is a bug in MS Exchange 2003 when sending to greylisting servers. Sometimes the server will fail to re-queue messages sent to some servers that implement greylisting. More information:

According to ozinm on our forums there is a possible hotfix available from Microsoft now:

UPDATE: The hotfix that Microsoft has released is available here:



Postini, which is a google service, applies the greylisting rules to incoming mails, however it doesn't work properly itself when used to send email to email servers that incorporates greylisting. The reason for this is the most common reason for greylisting failing: When a message is resent it does not appear to come from the same originating IPemail address as the first time.

Lyris listserve

The Lyris listserve software (from Lyris Inc.) is not compatible with greylisting. It appears that they are already aware of this, but not planning to do anything about it: