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Hy!
I have an on-premise postfix mail server which relay the e-mail to Exchange Online if recipient isn't local mailbox. I have an inbound connector in cloud and enabled the Enhanced Filtering. But when I send an email from externally to the cloud mailbox, the mail is received, but the header include the postfix server public IP address, so the Enhanced Filtering not working.
I notice that the Inbound connector is not use, I checked the connector report and see the following: From the internet without a connector. Why don't use the inbound connector from the postfix server mail?
Thanks.
How is the inbound connector configured? what are the settings?
What is the MX record set to?
MX is set to on-premise. The Inbound connector set on the picture.
Are you sure the Postfix is configured correctly to route to EOP? Does it have that cert with that subject name set to smarthost to EOP?
Yes, it is configured correctly. If the recipient not delivery locally, because the recipient in cloud, the postfix forward the email to the tenant own MX FQDN.
What depends on the M365 use the inbound connector? When I modify the connector to identify with the IP address, the problem is same, not using connector. I don't understand it.
I resolved the issue. When I create the Inbound connector, I stayed check in the: Retain internal Exchange email headers (recommended) option. I unchecked it and the inbound connector and the Enhanced Filtering works correctly.
Ok, that makes sense, this is not a hybrid config.
If you enabled enhanced filtering and SkipLastIP is set to $false, than you need to define the IPs to skip.
Yours are not set:
Typically you would set EFSkipLastIP $true
Did you follow?
https://learn.microsoft.com/en-us/exchange/mail-flow-best-practices/use-connectors-to-configure-mail-flow/enhanced-filtering-for-connectors
Hello Andy!
I set to EFSkipLastIP to true, but the M365 not remove the last IP from the header. I think the Exchange Online skip the inbound connector when the on-premise postfix relay the message to Exchange Online.
I check the Mail Flow reports on Exchange Online and see:
I tried to enter the postfix server public IP address in EFSkipIps attribute, but not resolve my problem.