Exchange 2010 Hybrid - Send Connector Questions


  • I set my on-perm. Exchange server 2010 on Hybrid mode of Exchange Online  (O365).
    I changed the MX record for receiving mails from Exchnage Online (O365). Should I modify the on-perm. Send Connector to Exchnage Online (O365) too?

    Question 1. How can I check my current mail flow? Is the Send Connector of on-perm. going to the Exchange Online (O365) already?
    If the on-perm. Send Connector set the “Use domain name system (DNS) ‘MX’ records to route mail automatically”, that mean my on-perm. users are using the Exchange Online (O365) gateway for outgoing mails?

    It is because my domain ( MX record changed to O365 already, that mean my on-perm. users are using the Exchange Online (O365) gateway for outgoing mails, right?
    > set type=mx
    Server:  []
    Non-authoritative answer:    MX preference = 0, mail exchanger =


    I have to change the Smart host to be my tenant’s Exchange Online SMTP host? Is it ‘’ also?

    2. Exchange 2010 multiple send connectors same domain
    For safe, can I add a new Exchange Online (O365) Send Connector and just assign some users on that for testing 1st only? 


    Saturday, August 26, 2017 12:02 PM

All replies

  • You can test mail flow using exchange powershell and 3rd party tools like SMTPDiag.exe , 

    Mail routing depends on your requirements if you don't want to let in external mail directly you can point MX to O365 or also you can directly point MX to your exchange server.

    test DNS recrods , nslookup -query=mx

    I would suggest you to read the following article;

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    Saturday, August 26, 2017 2:24 PM
  • Thanks Ed Crowley,

    Sample question:
    Can I modify the on-perm.'s Send Connector from “Use domain name system (DNS) ‘MX’ records to route mail automatically” to "Route mail through the following smart hosts"? If I want to let the outgoing emails of on-perm.'s users send by O365, should I fill the smart host as "" (Exchange Online SMTP address)??

    Monday, August 28, 2017 2:15 AM
  • Hi,

    We don't to change any setting for send connector (used to deliver message to Internet), the outbound mail flow will be directly send out in each side.

    The connector between local Exchange and Exchange Online is used for mail flow between them.
    And those connector will be auto-created after HCW configuration complete.

    By the way, is it the newest version of your local Exchange server (i.e. Exchange 2010 SP3 UR17)?
    If so, we can login Office 365 portal and download HCW to reconfigure hybrid environment.

    More information, for your reference:


    Allen Wang

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    Tuesday, August 29, 2017 2:51 PM