Why did only a partial list receive my email when it all shows in my sent items?

This problem is typically one of three issues which may occur when running Exchange 2010:

1) The user (or PoliteMail Service Account “user”) does not have adequate permissions to expand or send to the list

Symptoms: The user can successfully send to the list without PoliteMail, but NO mail is sent when using PoliteMail.

Resolution: Have your Exchange Admin ensure the PoliteMail Service Account has adequate permissions to expand and send to the desired distribution group.

2) The Exchange server-side throttling policy is impacting the ability of PoliteMail to perform the list expansion, especially when the distribution list > 5,000 recipients

Symptoms: When the user sends a tracked PoliteMail message, only part of the list gets sent to.

Resolution: The root cause of this issue is the server-side throttling policy on Exchange. When the PoliteMail Server attempts to expand a large distribtuion group, Exchange settings prevent that spike of activity. Specifically the list expansions query takes too much time to access Active Directory Domain Services (or Exchange/AD is otherwise too busy to respond in time). The problem can be avoided by increasing the RCAPercentTimeInAD parameter to a larger value by using the Set-ThrottlingPolicy cmdlet as detailed in http://support.microsoft.com/kb/2598291. If adjusting the throttling policy on Exchange is not possible, there is an Outlook 2010 hotfix package available for download from Microsoft.

3) A bug in Exchange 2010 results in partial sends (sometimes/inconsistently) when using PoliteMail

Symptoms:
When sending to an Outlook distribution group, only part of the list recieves the email, the remainder are never actually sent, despite PoliteMail recording the total number sent, and showing the email in Sent Items.

Please note that this error does not occur on every send, but randomly, depending upon the conditions of Exchange Server 2010 at the time of the send.

Resolution:
This problem can be fixed by applying the Update Rollup 3 for Exchange Server 2010 Service Pack 2 (information link only, not the actual update)

If you are unable to update your Exchange Server, PoliteMail offers a client hot-fix version which includes a work-around to this Exchange bug, and will enable the full send to go out.

In the first quarter of 2013 PoliteMail received a number of customer inquiries regarding partial sends, for users sending via the Outbox as well as via the Server using Active Directory distribution groups. Upon investigation, the common element was Exchange 2010 sp2, but the problem did not occur every time, however when it did occur, ‘buffer exception’ errors where logged.

Cause

The PoliteMail for Outlook add-in is a multi-threaded MAPI application that requests data from Exchange Server 2010.

Due to a bug in Exchange 2010, the PoliteMail MAPI application encounters MAPI_E_CALL_FAILED errors. Additionally, the Microsoft.Exchange.RpcClientAccess.BufferTooSmallException error is logged in the C:\Program Files\Microsoft\Exchange Server\V14\Logging\RPC Client Access server.

When sending via the Outbox, PoliteMail would be unable to report this error. When sending via the Server, the user would see a dialog showing the MAPI_E_CALL_FAILED error, and by clicking OK, PoliteMail would continue processing but would have lost some of the recipients as a result.

For more information read:

Member names are not displayed in a distribution list in Outlook 2010

MAPI errors occur when an Outlook 2007/2010 MAPI application tries to access an Exchange Server 2010 server

Random MAPI_E_CALL_FAILED errors in Exchange Server 2010