Forum Discussion

Copper Contributor

Jul 11, 2022

Solved

Different NDRs from 365

I have a tenant with 365. When I sent an email to an invalid recipient, 365 responds with: Remote Server returned '554 5.4.1 <test-org.mail.protection.outlook.com #5.4.1 smtp; 550 5.4.1 Recipient...

admin

exchange

AndresGorzelany
Jul 11, 2022
Hello,

This might be DBEB

https://docs.microsoft.com/en-us/exchange/mail-flow-best-practices/use-directory-based-edge-blocking

https://techcommunity.microsoft.com/t5/exchange-team-blog/in-deployment-directory-based-edge-blocking-for-exchange-online/ba-p/588872

AndresGorzelany

MVP

Jul 11, 2022

Hello,

This might be DBEB

https://docs.microsoft.com/en-us/exchange/mail-flow-best-practices/use-directory-based-edge-blocking

https://techcommunity.microsoft.com/t5/exchange-team-blog/in-deployment-directory-based-edge-blocking-for-exchange-online/ba-p/588872

TheRealJMartinez

Copper Contributor

Jul 13, 2022

Thanks Andres. That sounds like exactly what it is. Any idea why I receive enhanced NDR from some 365 customers and not from others?

AndresGorzelany
MVP
Jul 13, 2022
Probably because, a different component rejecting the message depending on DBEB enabled or not
- TheRealJMartinez
  Copper Contributor
  Jul 19, 2022
  AndresGorzelany Thank you for your assistance.