How can I limit the number of recipients for a message?

A. Using a new registry entry that was added as of 4.0 Service Pack 1 you can set the number of recipients for a message which is the sum of To:, cc: and bcc: (this includes personal distribution lists).

To implement perform the following:

1. Logon to the Exchange Server
2. Start the registry editor (regedit.exe)
3. Move to HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeIS\ParametersSystem
4. From the Edit menu select New - DWORD value
5. Enter a name of 'Max Recipients on Submit' (don't type the quotes) and press Enter
6. Double click the new value and set to the max number. Click OK
7. Close the registry editor

If a user attempts to send a message to more recipients than is designated by the Max Recipients on Submit parameter and the user has the new Emsmdb(32).dll, the following error message may be displayed when the user attempts to send the message:

The item could not be sent. The number of recipients on this message exceeds the upper limit configured by the administrator.

If a user attempts to send a message to more recipients than is designated by the Max Recipients on Submit parameter and the user DOES NOT have the new Emsmdb(32).dll, the following error message may be displayed when the user attempts to send the message:

The item could not be sent. The client operation failed.

More information can be found in Knowledge Base article Q126497 at http://support.microsoft.com/support/kb/articles/q126/4/97.asp.

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