Many administrators are familiar with setting size limits on e-mails inbound from outside the Exchange domain. However, there may be a situation where you want to limit the size of e-mails sent internally, from Exchange user to Exchange user. For instance, you might do this to thwart users from passing massive attachments to each other (and bulking up the size of the Exchange message database in the bargain).
One way to limit e-mail size is to enforce message size limits on each mailbox. This would be a problem, however, for an organization that has a great many mailboxes. Another way to enforce message size limits is by activating a function in Exchange that also controls message journaling, but additionally enforces any size limits set in the Message Transfer Agent (MTA) for local message delivery.
To enable message journaling and MTA message size restrictions, edit the Registry and go to the key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ MSExchangeIS\ParametersSystem. Add a REG_DWORD named No Local Delivery under this key and set it to the value 1. To change the MTA Message Size Maximum setting, open the Properties page for the MTA object and look on the General tab; this setting is calibrated in kilobytes.
One side effect of using this setting is that it does slightly increase the load imposed on the Exchange server. If users are accustomed to passing large files through e-mail, the limit can be set high (5MB or so), but administrators may want to provide users with some training in using shared folders, FTP sites or other methods for local file sharing if they need to pass files back and forth with each other.
Serdar Yegulalp is the editor of the Windows 2000 Power Users Newsletter.
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