We switched over to Office 365 and Outlook 365 in Jan 2021. We have noticed that it is normal for messages to be delayed 1-2 hours on occasion but in these cases we get no error message back in our email. In two instances, random messages were delayed by 8 hours. This is normal for this product, possibly due to high volume, or perhaps by a cluster of servers being down on the Microsoft end.



You may want to post this on a networking forum as the MX record is more of a networking issue and I'm not a network guy.