SIP Address Doesn’t Match Email Address


By default if your Lync SIP address doesn’t match your primary SMTP email address, then Outlook integration will not work. You can resolve this by disabling the client policy DisableEmailComparisonCheck using the following PowerShell command.




  1. What are the consequences then? Does the Outlook integration simple not work, or does the system simply use other methods to discover the mailbox, thus increasing the time or load on other Lync components? I've just worked with some messed up environments where it's a mixed bag, some are "correctly" setup, others are not.

  2. Hey Andrew, Does this apply to the main SMTP address being an alias? We have an environment where the SMTP address is being used as the main SIP address but its not a different domain. This is causing some problems with voicemail and Windows Mobile integrations.

    • Hey Steven,

      From what I understand you are saying that both your users SIP address and Exhange SMTP address are the same i.e both are [email protected]. If this is the case then DisableEmailComparisonCheck does not need to be enabled. If you give me a bit more information about your scenario I may be able to help further.

  3. We are a bit stuck with Lync 2013. We are using the UPN for the SIP but the Domain name is different from the Email domain. Message history is correctly being saved in Outlook but Lync cannot find it when you click on a user and select ‘find message history’.

    Any suggestions greatly appreciated

    • I’m not 100% off the top of my head, but this may require EWS connectivity. Do you know if EWS is working? If you hold the control button and right click the Lync task tray icon you can select “Configuration Information”. Within that you are interested in the status of “EWS Information” and “MAPI Information” – what state are they in?

  4. Hi Andrew,

    Sorry this reply is not very timely, but I have two domains that are federated for Skype use. The 1 domain has a setup where SIP matches the email of each users. The 2nd domain has a setup where SIP does not match the email of each user. Domain 1 cannot search by email the user of Domain 2 successfully. Only by entering the sip address can the user of Domain 1 connect to the user of Domain 2 over Skype. Is there a way to map each of those emails to sips in Domain 2 ? Our experts have come to the conclusion that it’s not possible. Can you advise if there is a seamless way for Domain 1 users to connect to Domain 2 users without having to put in a sip address (which looks very different than user name or email address–it’s actually some random characters)

    Many thanks for any advice,
    Paul Stanek

    • Hey Paul, so these are 2 separate SfB environments federating with each other? You want the users contacting the other party to be able to resolve them by email address rather than the different SIP address? If I have understood correctly then you are correct there is no way around this to my knowledge. The only workaround would be to add Outlook contacts and use the IM Address for SIP and Email for Email.

      • Hi Andrew,
        That’s correct, these are 2 separate SfB environments that are federated. Sorry to hear that there is no way around this, but thank you verymuch for your reply 🙂

        Have a good day!
        BR, Paul

  5. Try to add this registry on Client machine.

    Name: TrustModelData
    Type: REG_SZ
    Value will be Exchange domain name.


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