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Hello, I wanted to ask you how I should configure mail routing.
The organization is currently operating in a hybrid scenario. All messages are sent and delivered through Barracuda.
But we're finalizing the migration and want to switch all mail afterwards to o365 instead of On-Prem.
Now this is the scheme.
o365 currently has two connectors for the Barracuda. If we switch mail flow from Barracuda to o365. Users in On-Prem cannot receive messages with error: 554 5.4.14 Hop count exceeded - possible mail loop ATTR34
It turns out such a scheme.
Am I correct in understanding how to avoid this problem? I should create two other connectors instead of the incoming connector. So that all messages coming to domain.com (which is the accepted domain for the Exchange organization) are delivered to On-Prem. In this case, On-Prem receives or will be able to receive messages. And if the user is in O365, then his messages will be redirected back through on-prem to o365 using the technical address. To do this, a second connector is created that sends all messages to domain.onmicrosoft.com to o365.
Thank you.
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Hi @Mountain Pond ,
Based on your description, I want to confirm if you want your mail routing flow in below scenario: Internet mails - Barracuda -O365 -On-prem? Please correct me if I misunderstand your issue.
As far as I know, if you want to internet mails flow to O365 first, you should disable centralized mail transport. Detailed information on routing incoming Internet messages through the Exchange Online organization for your reference.
In addition, please refer to a blog on How to Configure Microsoft 365 for Inbound and Outbound Mail, and it indicates that you only need create one send connector to configure outbound mails. In the blog, it also mentions that each of your domains from which you want to be able to send email must be added to the Barracuda Email Security Gateway. Be sure to add all of your accepted Microsoft 365 domains to the Barracuda Email Security Gateway before configuring outgoing email in this section.
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Yes, corrent Internet mails - Barracuda -O365 -On-prem.
Yes, everything is set up correctly and everything works. But since there is still on-prem, messages cannot be delivered via o365.
Can the below diagram solve the problem?
Thank you.
Hi @Mountain Pond ,
You could try to disable the receive connector which is used for routing all messages from Barracuda IP address list and check if the issue continues.
In general, we need two connectors to route email between O365 and on-prem sever, and if you ran the Exchange Hybrid Configuration wizard, connectors that deliver mail between Microsoft 365 or Office 365 and Exchange Server will be set up already. We don't need create another new connector to route email between O365 and on-prem sever. Detailed information for your reference: Set up a connector from Microsoft 365 or Office 365 to your email server
Hope above help.
Hi @Mountain Pond ,
Is there any update on your issue? Does the issue disappear when you disable the connector which is used for routing all messages from Barracuda IP address list?
If you have any questions or needed further help on this issue, please feel free to post back. If the issue has been resolved, please accept the helpful replies as answers, this will make answer searching in the forum easier and be beneficial to other community members as well.