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Error: The messaging interfaces have returned an unknown error. Cannot resolve recipient.

  • I have configured outlook 2010 with one Exchange Online account, and one Google Apps for business account.  Everything seems to be working mostly OK. 


    However, I am encountering a single annoying problem which seems to strike some users with this configuration, and have been unable to solve it.

    Using the exchange online account, when I reply to some emails ONLY FROM CERTAIN PEOPLE, I get an error "The operation failed.  The messaging interfaces have returned an unknown error.  If the problem persists, restart Outlook.  Cannot resolve recipient."


    This seems to be limited to people whose email address appears in the "to" field in the following format:  lastname, firstname <>


    I have a contact set up for these people, and their email address is correct in the contact information.  As a matter of fact, when I hit "reply" and then erase the address that is entered there by outlook (in the above format) and then either click "TO" and pick their contact information, or I manually type their email address, everything works and the mail goes through.


    If I create a new profile with ONLY the exchange online account in it, everything works perfectly. 


    With google apps for business, you have to create the profile in outlook using the google app sync tool.  Then you add the exchange account.  There doesn't appear to be a way to add a google app sync account to an already existing profile with an exchange online account in it. 


    I'm at a loss on how to fix this.  It affects somebody I email multiple times a day and I have to keep erasing their reply address and re-entering it.


  • Hi Jeff,

    From your description, I notice this issue occurs when the Office 365 account and Google app account are configured in the same profile.

    I suggest you empty auto-complete list to check if this issue persists: Click File -> Options -> Mail -> Send Messages, and then click the Empty Auto-Complete List button.

    Based on my experience, there may be some conflicts for the two accounts in one Outlook profile. Here is a similar thread for your reference:

    Young Yang

  • Yes, I have tried emptying the auto-complete list.  It still does not work.  Do you know if Office 2013 has this same issue?

  • Hi Jeff,

    Based on the current situation, when the Outlook profile only contains the Office 365 account, this issue doesn’t occur. I suggest you use Office 365 account in the new profile. About Office 2013, you can test this issue on a machine with Office 2013 installed.

    Young Yang

  • I have considered that, but I cannot keep switching profiles because I need to monitor both email accounts throughout the day.  

  • Hi Jeff,

    Since this issue may be caused by the Outlook profile.
    You can create a new profile and set up the Exchange Online account first, then make sure if it works fine.
    If yes, you can add the other account to this Outlook profile and check if all accounts work fine.
    If yes, you can remove the old profile and use the new profile.

    Wilfred Ying

  • Thank you for your suggestion Wilfred.  Google Apps for business is configured with Outlook using the Google Apps Sync tool.  It creates a new outlook profile automatically.  Then you add the Exchange account to the profile.  Indeed, I think that this is the problem and that perhaps your solution might work, but I cannot find any instructions on how to add the Google Apps Sync account to an existing (working) profile with an exchange account in it.  I am still trying to determine if it's even possible to do that.  If MSFT could provide some guidance about whether the addressing issue I initially described affects Outlook 2013 as well, I would appreciate it, as this problem seems to affect many users and it seems like there is no definitive solution thus far.

  • Hi Jeff,

    As we lack information about the Google Apps account and the Google Apps Sync tool, I suggest you contact Google Apps support, maybe they can provide the solution of adding Google Apps account to an existing Outlook profile. Therefore, you can check if this issue persists.

    Based on my research, currently, there’s no official declaration whether Outlook 2013 has the same issue. If it is convenient for you, you can test it on a computer with Outlook 2013 installed.

    Young Yang

  • Outlook 2013 has the same problem: I found this discussion while searching for a solution to it!

    Windows 8 PC with Office 2013, both fresh, neither an upgrade.  Google Apps for Business-created profile using GOogle's sync tool, and an Office 365 account added.

    1 out of 1 people found this post helpful.

  • Thanks for posting that Daniel.  I am still suffering with this problem.  I have not tried Office 2013 because I haven't had the time.  I won't bother trying it now.  If you find a solution, would you mind posting it back here so it can help me and others like us?

  • I certainly will.  I have used Office 2013 since it was released but still don't like it as much as Office 2010 - the flat and monotone toolbars are harder to work with than Office 2010's colourful ones.

    I'm really a Google Apps user, and for a few months had been using Google Apps via IMAP because the Google Apps Sync application didn't support Windows 8 or Outlook 2013 until recently.  Once they updated it, I switched back to the Apps sync, but one of my main ways of sending email - an invoice generated in Sage 50 Accounts and saved into Outlook's Drafts folder ready for editing and sending, didn't work with the Apps Sync.

    I saw that it did work with an Exchange account in Outlook, so took out an Office 365 hosted Exchange mailbox, only to find that it breaks my ability to send far more email!

    My unlucky time with Outlook, the slow sync of IMAP, and make-do ways of syncing calendar and contacts have driven me to using Gmail for the Google Apps account, so I'm unlikely to spent long trying to figure out a way of satisfying Outlook because I'm just manually creating emails to send the PDF invoices and that's sufficient for now.

  • I am following up on jeffsmitty's original inquiry.  Same problem here.  Do we have an update or solution available?

    Thank you,


    0 out of 1 people found this post helpful.

  • If you are still using Outlook 2010 you can try a tool called ExtraOutlook.  This is designed to allow you to run two instances of Outlook at once, using different profiles. There is no support, but I have used this for over 7 years on various versions of Outlook without any problems (initially to connect to tow exchange servers in one profile before Microsoft supported this).

    Unfortunately it does not work with Outlook 2013.  

    On a more general note, it would be more helpful if Google and Microsoft would accept that many users do need to access mail from both Exchange and Google Servers and worked together on this problem.  As matters stand Google support's standard response is "take it to Microsoft" and Microsoft's is "take it to Google".

    The only practical way to run Google Apps (mail, calendar, etc) in Outlook  is using Google Apps Sync.  However as noted here, running it in the same profile as an Exchange account just doesn't work.

    There are two ways that Microsoft could actually help their customers with this issue

    1. Work with Google to identify and fix the problems in Google Apps Sync, or

    2. Modify Outlook 2013 to allow it to run multiple instances with different profiles - this is not such a good solution for the end user (I would rather just run one email client) but at least means that the solution is entirely within Mircosoft's control.  

    0 out of 1 people found this post helpful.