locked
Communication between office 365 and Exchange Server not happening RRS feed

  • Question

  • Hi Everone,

    I have configure a hybrid Setup and our Mx are pointed towards our EOP.The problem which i am facing is when some one send email from outside to onprem exchange Server.It is not reaching to the on-prem mailbox.Even if we send email from office365 to on prem its not sending to the intended mailbox in our onprem Exchange.From onprem to office365 the communication is fine.

    While configuring send connector in Office 365 i have add our EOP as a next hope.Is this the right configuration of a send connector or i should add something else as next hope in our 0365 send connector.I am attaching the screenshots of oo365 send connector as well.

    The NDR  which sender is receiving back is .

    Error Details
    Reported error: 554 5.4.14 Hop count exceeded - possible mail loop ATTR34 [DX2ARE01FT005.eop-are01.prod.protection.outlook.com]
    DSN generated by: DXXSPR01MB0004.AREP273.PROD.OUTLOOK.COM
    Remote server: DX2ARE01FT005.mail.protection.outlook.com

    

    Wednesday, May 13, 2020 10:36 AM

Answers

  • Your outbound connector to on-prem is configured wrong. The smarthost would be an on-prem server, not Office 365.

    Didnt the Hybrid Wizard set this up for you already or is this an additional connector ?

    verify its configured correctly

    https://docs.microsoft.com/en-us/exchange/mail-flow-best-practices/use-connectors-to-configure-mail-flow/set-up-connectors-to-route-mail

    • Marked as answer by Shong Chen Wednesday, May 13, 2020 12:28 PM
    Wednesday, May 13, 2020 10:57 AM
  • Thank you Adny for Reply,

    Actually HCW didn't configure it for me i run that multiple time.Should i give the IP of our on prem Spam filter  in the next hope or any other public IP?

    Thank YOU!



    It should be the FQDN ( preferred) or public IP of your on-prem Exchange Servers that you are using for SMTP communication between on-prem and Exchange Online.  Your SPAM Filter, I dont what that is, but you cant have any non-Exchange Server between your on-prem org and Office 365 when in hybrid mode

    https://docs.microsoft.com/en-us/exchange/transport-routing

    Don't place any servers, services, or devices between your on-premises Exchange servers and Office 365 that process or modify SMTP traffic. Secure mail flow between your on-premises Exchange organization and Office 365 depends on information contained in messages sent between the organization. Firewalls that allow SMTP traffic on TCP port 25 through without modification are supported. If a server, service, or device processes a message sent between your on-premises Exchange organization and Office 365, this information is removed. If this happens, the message will no longer be considered internal to your organization and will be subject to anti-spam filtering, transport and journal rules, and other policies that may not apply to it.

    • Marked as answer by Shong Chen Wednesday, May 13, 2020 12:28 PM
    Wednesday, May 13, 2020 11:37 AM
  • Ok Thank you!

    I am going to check with my Network team on that as it was refucsing the connection.One more thing if you could please tell me if a mailbox is present onprem and email come through EOP will there be some specific Transport rule to forward that email toward this connector or something else?

    Best Regards.

    The outbound connector from 365 to on-prem will handle the routing. That article I linked above describes the mail flow.

    Its important that the accepted domain is set to internal relay in Office 365 as well if you have any on-prem recipients that arent represented in Office 365 ( or use on-prem Public Folders that arent sycned, etc..)

    • Marked as answer by Shong Chen Wednesday, May 13, 2020 12:28 PM
    Wednesday, May 13, 2020 12:19 PM

All replies

  • Your outbound connector to on-prem is configured wrong. The smarthost would be an on-prem server, not Office 365.

    Didnt the Hybrid Wizard set this up for you already or is this an additional connector ?

    verify its configured correctly

    https://docs.microsoft.com/en-us/exchange/mail-flow-best-practices/use-connectors-to-configure-mail-flow/set-up-connectors-to-route-mail

    • Marked as answer by Shong Chen Wednesday, May 13, 2020 12:28 PM
    Wednesday, May 13, 2020 10:57 AM
  • Thank you Adny for Reply,

    Actually HCW didn't configure it for me i run that multiple time.Should i give the IP of our on prem Spam filter  in the next hope or any other public IP?

    Thank YOU!



    • Edited by Shong Chen Wednesday, May 13, 2020 11:31 AM
    Wednesday, May 13, 2020 11:16 AM
  • Thank you Adny for Reply,

    Actually HCW didn't configure it for me i run that multiple time.Should i give the IP of our on prem Spam filter  in the next hope or any other public IP?

    Thank YOU!



    It should be the FQDN ( preferred) or public IP of your on-prem Exchange Servers that you are using for SMTP communication between on-prem and Exchange Online.  Your SPAM Filter, I dont what that is, but you cant have any non-Exchange Server between your on-prem org and Office 365 when in hybrid mode

    https://docs.microsoft.com/en-us/exchange/transport-routing

    Don't place any servers, services, or devices between your on-premises Exchange servers and Office 365 that process or modify SMTP traffic. Secure mail flow between your on-premises Exchange organization and Office 365 depends on information contained in messages sent between the organization. Firewalls that allow SMTP traffic on TCP port 25 through without modification are supported. If a server, service, or device processes a message sent between your on-premises Exchange organization and Office 365, this information is removed. If this happens, the message will no longer be considered internal to your organization and will be subject to anti-spam filtering, transport and journal rules, and other policies that may not apply to it.

    • Marked as answer by Shong Chen Wednesday, May 13, 2020 12:28 PM
    Wednesday, May 13, 2020 11:37 AM
  • Ok Thank you!

    I am going to check with my Network team on that as it was refucsing the connection.One more thing if you could please tell me if a mailbox is present onprem and email come through EOP will there be some specific Transport rule to forward that email toward this connector or something else?

    Best Regards.

    Wednesday, May 13, 2020 12:08 PM
  • Ok Thank you!

    I am going to check with my Network team on that as it was refucsing the connection.One more thing if you could please tell me if a mailbox is present onprem and email come through EOP will there be some specific Transport rule to forward that email toward this connector or something else?

    Best Regards.

    The outbound connector from 365 to on-prem will handle the routing. That article I linked above describes the mail flow.

    Its important that the accepted domain is set to internal relay in Office 365 as well if you have any on-prem recipients that arent represented in Office 365 ( or use on-prem Public Folders that arent sycned, etc..)

    • Marked as answer by Shong Chen Wednesday, May 13, 2020 12:28 PM
    Wednesday, May 13, 2020 12:19 PM