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Exchange 2013 421 4.3.2 Service not available RRS feed

  • Question

  • Hi all,

    Everything have been working fine until lately. Not sure when problem started, but when add an IP address to new(or old) receive connector to allow relay we get error 421 4.3.2 Service not available when try to telnet to Exchange server.

    Tried to delete connector and setup new (as FrontendTransport), still get same error when try to telnet.

    Mail flow seems to work fine.

    Even when try to telnet between exchange servers, we get same error message. Same problem also happens on the 2nd exchange server.

     No firewall between client and exchange server or between Exchange servers. Windows firewall also turned off for all profiles without any help.

    Restart transport service did not help. Found similar article, but none of solutions helped: https://social.technet.microsoft.com/Forums/office/en-US/cd03793b-9e99-474e-8f25-11275652882f/exchange-2013-stops-receiving-external-email-after-about-8-hours?forum=exchangesvradmin

    Any tips for further troubleshooting?

    Thanks!


    Please mark as helpful if you find my contribution useful or as an answer if it does answer your question. That will encourage me - and others - to take time out to help you. Thank you! Off2work

    Monday, August 14, 2017 9:12 AM

Answers

  • Found out the cause..seems to be firewall between after all and NAT was wrong setup...

    thanks!


    Please mark as helpful if you find my contribution useful or as an answer if it does answer your question. That will encourage me - and others - to take time out to help you. Thank you! Off2work

    • Marked as answer by Off2work Monday, August 14, 2017 10:05 AM
    Monday, August 14, 2017 10:05 AM

All replies

  • Found out the cause..seems to be firewall between after all and NAT was wrong setup...

    thanks!


    Please mark as helpful if you find my contribution useful or as an answer if it does answer your question. That will encourage me - and others - to take time out to help you. Thank you! Off2work

    • Marked as answer by Off2work Monday, August 14, 2017 10:05 AM
    Monday, August 14, 2017 10:05 AM
  • Hi, Off2work 

    My dear old friend, thanks for your question and solution sharing : )


    Best Regards,

    Lynn-Li
    TechNet Community Support


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

    Tuesday, August 15, 2017 2:27 AM
    Moderator