Forum Discussion
FerdieC
Apr 17, 2023Copper Contributor
Exchange online users can't send or receive email in Hybrid configuration.
Hello, I'm testing a hybrid deployment with Exchange 2019 on prem. The hybrid setup seemed to go smoothly and I can migrate mailboxes between on-prem and online and back again. The problem I'm hav...
Dan_Snape
Apr 18, 2023Steel Contributor
Have you configured centralised mail flow (all outgoing mail from Exchange Online routes via the on-prem Exchange servers)? Without having much detail, it looks like your on-prem network is blocking connections from Exchange Online to your on-prem Exchange server. Look at the connector in Exchange Online and make sure it validates fine. A message trace performed in Exchange Online will also show some more information which may shed some light on the issue
- FerdieCApr 18, 2023Copper Contributor
Thanks Dan.
Centralized mail transport is Not enabled, so email to the internet should route directly out of Exchange Online, yet I get the "Access denied, traffic not accepted from this IP" bounce back.
There are 2 connectors in Exchange online, Inbound (Your Org to O365) and Outbound (O365 to Your Org). The Outbound connector successfully validates and the on-prem mailbox receives the validation email. Inbound mail from the internet routes through the on-prem server and are delivered to the online mailbox, so the Inbound connector looks like it's working too.
- Dan_SnapeApr 20, 2023Steel ContributorYou've said you're only testing hybrid.....so it's possible the problem is outlined here https://learn.microsoft.com/en-us/exchange/troubleshoot/email-delivery/ndr/fix-error-code-5-7-700-through-5-7-750#57708-access-denied-traffic-not-accepted-from-this-ip