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#550-Verification failed for 550-No such user at this domain 550 Unable to verify sender ## RRS feed

  • Question

  • Hi, 

    One of our users has tried to email an email address and received the following error #550-Verification failed for  550-No such user at this domain 550 Unable to verify sender ##

    I am able to email the address fine and cannot seem to figure out where the user lies. He can email other people fine but is unable to email this one address. 

    Can anyone help please? 


    MCP,MCSA,MCSE,MCTS,MCITP Enterprise Administrator,Citrix Certified Administrator

    Tuesday, July 2, 2013 10:27 AM

All replies

  • Hi,

    Does this email send to external user ?

    Please check if the email address is correct. Also check if you can ping the server or domain , if the email address is a

    external address.

     By the way, do you use exchange server?


    Wendy Liu
    TechNet Community Support

    Thursday, July 4, 2013 8:52 AM
    Moderator
  • Hi, 

    Yes we use exchange 2010 sp1 in hosting mode. The recipients address is correct as I can email him from the same hosted solution. The user can email everyone else absolutely fine. It is just this one recipient that he cannot 


    MCP,MCSA,MCSE,MCTS,MCITP Enterprise Administrator,Citrix Certified Administrator

    Thursday, July 4, 2013 3:39 PM
  • One thing specific about our environment which I think influences this is that email leaves directly from the mail box servers but then comes in via a tmg server so any auth lookup would see the same ip 

    I believe we had the same issue with our email domain and did something to stop this but  cannot remember what we did. 


    MCP,MCSA,MCSE,MCTS,MCITP Enterprise Administrator,Citrix Certified Administrator

    Friday, July 5, 2013 9:05 AM