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Error code: -18500 in Outlook 2011 on Exchange 2010 when accepting meeting invites due to ShoreTel Meeting inegration

    Question

  • Hello,

    Environment

    • Installed a Shoretel VOIP system with Outlook for PC integration for contacts and meeting scheduling
    • Shortly after upgraded from Exchange 2003 to 2011

    Shortly after our Exchange install some of our Outlook 2011 for Mac and OWA users cannot send acceptance emails for meeting requests. The steps to recreating the issue in my environment are as follows:

    1. Meeting invite sent to affected Outlook 2011 user on Exchange 2010 from another user either through Outlook 2007/2010/2011,OWA,or ActiveSync Device
    2. Affected user accepts (with or without comments) or declines meeting invite 
    3. Meeting gets added (or not if declined) to the affected users calendar and denial/acceptance email is queued locally in Outlook 2011
    4. Affected user gets the following error : HTTP error. The server cannon fulfill the request. Mail could not be sent. Account Name "EXCHANGE" Error code: -18500
    5. Acceptance/denail never makes it to the user sending the invite.
    In troubleshooting this issue i also realized that automatic acceptance of meeting request send to Room Mailboxes also didn't work for some Outlook 2007 and 2010 users. I finally narrowed it down to a feature in the Shoretel VOIP communicator client that has an optional calendar plugin that when installed puts the user's deskphone in voice mail only mode when they are in a meeting. The problem is that this adds or changes the way the Calendar item is handled by other Exhcnage cleints resulting in the issues described above.
    I tried uninstalling the feature, removing the mail account and signing into another computer but the integration follows the persons account. Specifically it follows only their calendar. On the other hand any shared calendars they have access to work just fine and don't show the integration. At this point i'm guessing the program does some sort of mailbox level changes to the calendar that only outlook for PC clients can see. Does anyone have any idea how to confirm this or the best way to research if this is actually the problem? 
    Saturday, August 06, 2011 3:38 PM

Answers

  • Hi,

     

    First please verify if the issue occur to all the MAC users.

     

    Please verify if the issue only occur to meeting which is invited from certain person.

     

    Please check if meeting organizer use custom form for meeting requests. Default form of calendar should be IPM.Appoitment.

     

    Regards,

    Xiu

    • Marked as answer by Iczersigma Monday, August 22, 2011 2:16 AM
    Monday, August 08, 2011 8:09 AM

All replies

  • Hi,

     

    First please verify if the issue occur to all the MAC users.

     

    Please verify if the issue only occur to meeting which is invited from certain person.

     

    Please check if meeting organizer use custom form for meeting requests. Default form of calendar should be IPM.Appoitment.

     

    Regards,

    Xiu

    • Marked as answer by Iczersigma Monday, August 22, 2011 2:16 AM
    Monday, August 08, 2011 8:09 AM
  • Ok so I have an issue where out going cal invites and mal does nt send. I get the HTTP

    HTTP error. The server cannon fulfill the request. Mail could not be sent. Account Name "EXCHANGE" Error code: -18500

    Env. Mac OS X 10.6 Office 2011  14.1.0

    but otherbrand new mail goes just fine as do some other invites?

     

    People are missing my meetings as a result.

     

    Any help appreciated...

    Bryan

    Monday, August 08, 2011 8:05 PM
  • Hi Bryan,

    Do you have issue when you send meeting invitation,you get http error or the same as Iczersigma's: cannot send meeting accept response?

    Xiu

     

    Tuesday, August 09, 2011 6:10 AM
  • Hi Iczersigma,

    How is the issue now?

    Please feel free to update here.

    Xiu

    Friday, August 12, 2011 3:01 AM
  • First off I forgot to put notifications on this post so after I figured out what the issue was I decided to post back here and saw that Xiu had mentioned what the issue was. Basically the Shoretel VOIP communicator client had changed the default calendar form from IPM.Appoitment to Shoretel Appointment. This form contains some modifications that Outlook 2011, OWA, and resources mailboxes don’t like. I’m currently waiting on Shoretel support to provide an update version, in the meantime changed the everyone back to the default calendar form. 

    Monday, August 22, 2011 2:20 AM
  • Glad to hear it works now.

    Xiu

    Monday, August 22, 2011 2:21 AM