In the last month or so, I have been notified of multiple emails being received a day or two after they were sent as per the time stamp on the email. Our mail server is Exchange 2007 R2.
Everyone of the delayed emails was sent via Googles mail server.
Here an NDR from one of the senders:
From: Mail Delivery Subsystem <mailer-daemon@googlemail.
Subject: Delivery Status Notification (Delay)
Date: September 9, 2016 at 4:11:24 PM EDT
This is an automatically generated Delivery Status Notification
THIS IS A WARNING MESSAGE ONLY.
YOU DO NOT NEED TO RESEND YOUR MESSAGE.
Delivery to the following recipient has been delayed:
Message will be retried for 1 more day(s)
Technical details of temporary failure:
read error: generic::failed_preconditi
on: read error (0): error
----- Original message -----
I found this link
which suggests it has to do with the setup of sender's SPF record but we are having this issue with multiple email domains who uses google mail servers.
Coincidentally, the only thing I change recently was my SPF record "v=spf1 mx a ip4:18.104.22.168/32 -all" so it be maybe related to this delay problem? I am not sure.
Any help would be appreciated.