Exchange 2003 has a new security feature, enabled by default, that could be a problem for administrators who use scripts or batch files to send mass mailings.
If a script or batch file is used to send more than 250 messages or 100 attachments, Exchange 2003 detects this and may block the messages/attachments from being sent. When this happens the server will log an error with the event ID 9646.
Clearly the reason for this is to limit the amount of damage that a rogue script or worm can do, but it also has the potential of interfering when you are legitimately using a script to send mail in bulk.
The default maximum for the affected object type is controlled by a Registry entry on the computer running Exchange Server 2003. This default can be edited, but it should only be done on machines where this limit is a genuine hindrance and where there are appropriate safeguards against rogue scripts.
Follow these 6 steps to edit the default:
- Open the Registry on the Exchange Server 2003 computer and navigate to HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesMSExchangeISParametersSystem.
- Add a new key (not a value, but a whole subkey) named MaxObjsPerMapiSession.
- Within this new key, add two DWORD values: objtMessage and objAttachment.
- Set the value of objtMessage to the maximum number of message objects that can be automated at once.
- Set the value of objAttachment to the maximum number of attachment objects that can be automated at once.
A good starting value for both of these is 500.
- Close the Registry. The changes will take effect immediately.
Note that relying on scripting to perform mass mailings may not be the best idea, and that an actual commercial mass-mailer or a simple delivery list in Exchange may accomplish the same results with less effort.
Serdar Yegulalp is the editor of the Windows 2000 Power Users Newsletter. Check out his Windows 2000 blog for his latest advice and musings on the world of Windows network administrators – please share your thoughts as well!