Meeting Forward Notification issue: server sends multiple MFNs to organizer

Hi,

Exchange 2013 CU7 on Server 2012 R2.

We have separated the roles into mailbox server and front end.  Mailbox servers are installed on physical servers, front end is virtualized. 

We still have Exchange 2007 SP3 Rollup 10 in the environment but not hosting any user mailboxes.

The issue is when someone forwards a meeting invite, the MFN is delivered many times to the organizer. In some cases 100s of times.  I have increased logging levels on all of the  MSExchangeMailboxAssistants\ sub-categories on the mailbox server reported in the headers but see nothing useful in helping to troubleshoot.

Any tips on where to go from here are greatly appreciated.

March 20th, 2015 4:04pm

Hi Blmatx,

According to your description, it seems like an outlook client issue,.

I recommend you try the following method to check if you can reappear the issue:

Let the user use OWA to forward the meeting invite

In addition, I also recommend you refer to the following article to understand the behavior of MFN:

Behavior of Meeting Forward Notifications

Depending on the client of the organizer, the Exchange version of the attendee forwarding the meeting, and the organization membership of both parties, the meeting forward notification can either be sent by Exchange or Outlook, or neither product.

Best practices when using the Outlook Calendar

We generally recommend that an attendee not forward a meeting if they are not in the same Exchange organization as the organizer, unless all of the following conditions are true:

  • The attendee is using Microsoft Outlook 2010 or newer.

  • The attendees Exchange Administrator allows meeting forward notifications to be sent to remote domains.

  • The organizer is using a Microsoft Outlook client.

In the case of an attendee that uses a non-Exchange mail system, we generally recommend not forwarding a meeting, unless all of the following conditions are true:

  • The attendee is using Microsoft Outlook 2010 or newer.

  • The organizer is using a Microsoft Outlook client.

Best re

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March 23rd, 2015 4:54am

Sorry I forgot to provide client details in the original post.  I was able to reproduce with OWA to OWA and only forwarding to an account internal to the same organization/server/db as the other 2 accounts used.

I had a maintenance planned for this weekend and rebooted every Exchange server in the landscape.  Since then I have not been able to reproduce the issue.  Hopefully it's gone.

March 23rd, 2015 11:43am

It's back. As suggested I am testing with only OWA clients.

Echange 2013 OWA client A sends a meeting request to Exchange 2013 OWA client B.

Exchange 2013 OWA Client B forwards the meeting from the inbox to Exchange 2013 OWA client C.

Exchange 2013 OWA client A receives hundreds of MFN messages from the Exchange Server.

The current test meeting was forwarded 20 minutes ago and MFNs are still coming in to the originating mailbox.

Any server side suggestions?

Thanks for any suggestions!

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March 25th, 2015 10:26am

Resolved.  The SystemMailboxes were offline and that was causing the issue.
April 1st, 2015 5:04pm

Resolved.  The SystemMailboxes were offline and that was causing the issue.
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April 1st, 2015 9:02pm

Hi BLMATX

I have the same issue with MFN.

Could you tell me which steps you took to solve this issue?


  • Edited by Techweg 17 hours 33 minutes ago
June 22nd, 2015 9:52am

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