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Can't sign on to Office 365 using Lync for Mac

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Just signed up for Office 365 P1 and am able to sign into Lync on Windows, but when I try to sign in on my Mac (10.6.8) with the new Lynch for Mac client i get "Sign in to Microsoft Lync failed because the service is not available or you may not be connected to the internet". I know I'm connected tot he internet, I've disable my firewall, i'm using my O365 email/pw combination with auto configure enabled, and i have a license for it. Anyone know what's going on here?



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  • Is there any update on this please?    Just trying this now, and amazed that this does not work.

  • Same here, Nick.

    How did this question get answered, BLeitner?

  • Unfortunately I've heard nothing more than what's in this thread, and this question WAS NOT ANSWERED.

  • Hi BLeitner,

    Given the current situation, you could provide your domain information for us to further research. Since this is your privacy, I will send a private message to you to request your domain information. Therefore, you could reply me through private message.

    To access the private message with the subject of <Domain Information>:

    1.Please go to the Your details section on the right side of the community site.

    2.Click Private messages.

    3.Click the subject title of the response to read the message and reply with your domain information.

    Anna Guo

  • Hi Anna,

    This is Simon Wong from Hong Kong. I have users in Hong Kong and Canada who cannot log on to Lync Online from iMac. From your message means that is not the Office 365 problem. That is a individual user problem. Is that right?

    Thanks in advance for your clarification.

    Simon Wong/Hong Kong

  • Hi Simon,

    To troubleshoot the issue, you can set Lync for Mac using manual configuration by following these steps:

    1.In the upper-right area of Lync, click the Gear icon to open the Options page.

    2.In the Lync - Options dialog box, click Personal.

    3.Next to the sign-in address, click Advanced.

    4.Make sure that Manual Configuration is selected and that the configuration values are exactly as follows:

    ◦Internal server name or IP address:

    ◦External server name or IP address:

    You may also refer to the link below for detailed information about Lync for Mac for Enterprise Plan.

    If the problem still cannot be resolved, to better follow up the issue, please post a new thread about the error encountered and the detailed steps that you have taken.

    Anna Guo

  • Thanks very much for your quick reply. I will send your instructions to the end-users and ask them to try your solution.

    Thanks again and have a nice day,


  • Hi BLeitner,

    Based on the current troubleshooting, there might be different causes for this issue. I noticed that we might need to check the specific configuration on your side during the continue troubleshooting. You may need to provide other personal information about the issue. To avoid publishing some personal information, I would send you another private message. Please check it on the community side.

    You can reply by using the form in that private message.

    Anna Guo

  • My colleague told me that your solution does not work.



  • Hi All,

    You may check whether there is any certificate in your keychain marked as “Unknown”. If so, please remove the unknown certificate from keychain: go to Keychain Access and search for Unknown, then delete it.

    After doing this, you could check if Lync for Mac would work or not.

    Anna Guo

  • I don't have a cert named "unknown"

  • I suggested removing the certificate already, on 10.7.2 it works...
  • Again, I don't have a cert named "unknown" so this can't really can't be an answer to my problem. I am also not on Lion, I'm on Leopard, 10.6.8.

  • Hello BLeitner,

    Can this problematic user logon to Lync online From a Windows client? If yes, I suggest you try the following steps to troubleshoot this problem.

    1. Remove all the certificate that issued by "Communications Server" in Keychain Access from Mac client computer.

    2. Re-configure your Mac client with instructions in following article.

    Set up your Mac for Office 365

    3. Reboot the Mac client and configure Lync client on Mac with steps provided by Anna in previous post.

    If the problem persists, you may refer to the steps mentioned in following article to resolve the problem.

    How to troubleshoot authentication and connectivity issues in Lync Online

    Thank you.

    Jack Sun

  • Hi Anna, I removed the Unknown certificate from the keychain, but I am still not able to log on.  I am on Lion. Can you help?