Exchange online issue - users can't receive external email

[localzuk]

If anyone is having issues with emails being sent to you today and you use Exchange Online as part of Office 365, it seems they have an ongoing issue due to a failed migration.

 

The symptoms are that when someone external emails you, they get a 550 5.7.64 TenantAttribution; Relay Access Denied error.

 

This confused me a lot, as I couldn't figure out how external users were being treated as internal users trying to relay email. 

 

[jmak]

This started for us in the middle of last night. We were made aware that it was a Microsoft issue and they were working in it 

 

Ours was resolved by 11am

[Alis_Klar]

Out of interest do you have the Microsoft365 Admin mobile app?

 

it sends loads of advisories about issues they have.

 

seems to be lots of false positives tho so not something I’ve found that useful when we’ve had issues which seem to be more frequent in the last few months?!

Edited March 21, 2025 by Alis_Klar

[PotNoodleTech]

This should be fixed now - at least it was in Wales at approx 9pm last night.  Got all the emails that were waiting from yesterday come through in one big pile with the wroing "sent" times etc.