Forum Discussion
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 having is that online mailboxes cannot send to anyone and can only receive external email (which are routed through the on-prem server). The bounce back received are all similar, whether the email was on-prem to online, online to on-prem, or even online to online. this is the bounce back message for emails originating from Exchange Online to either an on-prem account or another online account.
Generating server: YQBP288MB0097.CANP288.PROD.OUTLOOK.COM
Remote server returned '550 5.7.708 Service unavailable. Access denied, traffic not accepted from this IP. For more information please go to http://go.microsoft.com/fwlink/?LinkId=526653 AS(7230) [YQBP288MB0020.CANP288.PROD.OUTLOOK.COM 2023-04-17T20:39:02.347Z 08DB3E6A08BC4E61]'
A similar bounce back is received sending from on-prem to online. I'm not sure which IP is being referenced since the mail doesn't leave the Microsoft environment.
Any help would be appreciated.
Ferdie
- 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
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.
- You'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
