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Julian12's avatar
Julian12
Brass Contributor
Apr 23, 2020

Teams calendar not syncing with exchange on-prem calendar

Hello,

I have a problem with the calendar sync between exchange online/Teams for a customer.

I configured Azure AD Connect with the hybrid option and users are synced to the cloud and licensed with O365 E3.

I setup exchange hybrid on an exchange server 2016 CU11 with the new version of the Hybrid Wizard, ending with the OAuth error after the first run. So I configured OAuth manually with the docs.microsoft manual and calendar sync was working, for 1 day. At the next day it wasn't working and I couldn't get it running again since then, 3 weeks ago.

 

I checked all OAuth config elements, reastablished them individually, startet the Hybrid Wizrad several times, always ending with the OAuth error. I tested with teh test-oauthconnectivity cmdlet in both directions which ends always successfull, restarted the server and services several times, checked the availability service and with the remote connectivity analyzer for free/busy and everything was successful but sync is still not working again.

 

Can someone help me with this issue or has tipps to chekc further?

 

Kind Regards

Julian

Calendar
exchange
OAuth
Sync
teams

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  • ChristianBergstrom's avatar
    ChristianBergstrom
    Silver Contributor
    Apr 23, 2020

    Julian12 Hello, can this assist you perhaps? https://docs.microsoft.com/en-us/exchange/hybrid-deployment/troubleshoot-a-hybrid-deployment

    • Julian12's avatar
      Julian12
      Brass Contributor
      Apr 23, 2020

      ChristianBergstromThx for the Link, I went through it an 2 things occured:

      THe Inbound SMTP Mail test failed with error: 550 - Mailbox unavailable. The server response was: No RDNS entry for IP_ADDRESS

      I think this is not problematic as this test fails too for a customer where sync is working.

      Another issue is the used certificate which is configured only for the IIS service and not for SMTP. I tried to add SMTP via GUI and with exchange commandline but smtp service isn't added. I don't know this happens now as I'm logged in with the Administrator account and no error messages are displayed.

       

      Besides these 2 isssues everything went fine.

      Do you have an idea why adding the cert to the SMTP service is failing?

      • ChristianBergstrom's avatar
        ChristianBergstrom
        Silver Contributor
        Apr 23, 2020

        Julian12 Hello Julian, you mean nothing happens when you run this 'Enable-ExchangeCertificate <thumbprint> -services SMTP'?

         

        I was going to suggest the solution described here https://support.microsoft.com/en-nz/help/2989382/can-t-receive-mail-in-a-hybrid-environment but as you cant add smtp it's a problem.

         

        Have you had a look at this as well? https://docs.microsoft.com/en-us/exchange/architecture/client-access/assign-certificates-to-services?view=exchserver-2019

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