Turning on Greylisting on Server prevents any incoming mail being received.

Hello all,

Very recently we have received complaints of mail not functioning on one of our virtual servers. Upon investigation this seemed to be caused by GreyListing being enabled. When this is turned off mail functions normally in both directions.

However when this is turned on outgoing mail continues to function however incoming mail ceases to be delivered.

This is the postfix log with greylisting enabled (I have changed some of the names for privacy)

Feb 28 23:00:17 host01 postgrey[1991]: action=greylist, reason=new, client_name=mail-oln040092069063.outbound.protection.outlook.com, client_address=, sender=testuser@outlook.com, recipient=user@domain.uk
Feb 28 23:00:17 host01 postfix/smtpd[20579]: NOQUEUE: reject: RCPT from mail-oln040092069063.outbound.protection.outlook.com[]: 450 4.2.0 user@domain.uk: Recipient address rejected: Greylisted, see http://postgrey.schweikert.ch/help/domain.uk.html; from=testuser@outlook.com to=user@domain.uk proto=ESMTP helo=<EUR02-VE1-obe.outbound.protection.outlook.com>

At the moment we have had to leave grey listing off to ensure mail is delivered but we don’t want to stay that way for long. Does anyone have any possible steps we can take to resolve this issue.

Thanks in advance

Can anyone help with this?

Your first rejection took place at 23:00:17. I do not see a second rejection.

This is what it is about:

Greylisting is a method of defending e-mail users against spam.
A mail transfer agent (MTA) using greylisting will “temporarily reject” any email from
a sender it does not recognize. If the mail is legitimate the originating server will try again after a delay, and if sufficient time has elapsed the email will be accepted.