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420 4.2.0 Recipient deferred because there is no Mdb RRS feed

  • Question

  • Hello, 

    we just changed our mailflow to use EOP.  We have thousands of users, only one user (so far) has experiencing problems receiving external emails.

    420 4.2.0 Recipient deferred because there is no Mdb

    All mailboxes are on-premises,  no hybrid.   

    There is no licence assigned to this user via O365 admin center. 

    We added secondary smtp this account, and external email was delivered.    We dont see any problem in AD attributes so far, everything worked before switching to EOP. 

    Guesses?

    Tuesday, March 31, 2020 7:08 AM

Answers


  • We added O365 license (including Exchange), then we removed the license.  Something happened  in background and issue was solved. 

    • Marked as answer by Mekac Tuesday, March 31, 2020 8:48 AM
    Tuesday, March 31, 2020 8:48 AM

All replies


  • We added O365 license (including Exchange), then we removed the license.  Something happened  in background and issue was solved. 

    • Marked as answer by Mekac Tuesday, March 31, 2020 8:48 AM
    Tuesday, March 31, 2020 8:48 AM
  • Hi Mekac,

    Glad to hear that your issue has been resolved, thanks for your sharing!

    Regards,

    Joyce Shen


    Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.

    Wednesday, April 1, 2020 2:44 AM