Configure SMTP filter buffer overflow thresholds

To configure SMTP filter buffer overflow thresholds

In the console tree of ISA Server Management, click Add-ins.
In the details pane, on the Application Filters tab, click SMTP Filter.
On the Tasks tab, click Configure Selected Filter.
On the SMTP Commands tab, click the applicable command, and then click Edit.
In SMTP Command Rule, select Enable SMTP command.
In Maximum Length, type the maximum length of the command line for the commands.

Notes

To open ISA Server Management, click Start, point to All Programs, point to Microsoft ISA Server, and then click ISA Server Management.
For ISA Server 2006 Enterprise Edition, expand Microsoft Internet Security and Acceleration Server 2006, expand Arrays, expand Array_Name, expand Configuration, and then click Add-ins.
For ISA Server 2006 Standard Edition, expand Microsoft Internet Security and Acceleration Server 2006, expand Server_Name, expand Configuration, and then click Add-ins.

Important

To add a new command, click Add and type the command name in SMTP Command Rule.
When a client uses a command that is defined but disabled, the filter closes that connection.
When a client uses a command that is unrecognized by the SMTP filter, no filtering is performed on that message.
Only commands on incoming traffic are filtered by the SMTP filter.
Only simple SMTP commands can be added.
If a client uses the TURN command, all e-mail messages will be dropped by the filter.
The RFC considers the AUTH command as part of the MAIL FROM command. For this reason, the SMTP filter blocks MAIL FROM commands only when they exceed the length of the MAIL FROM and AUTH commands issued (when AUTH is enabled). For example, if you specify a maximum length of MAIL FROM as 266 bytes and AUTH as 1,024 bytes, the message will be blocked only if the MAIL FROM command exceeds 1,290 bytes.

Get latest ISA Server content at ISA Server Guidance(http://www.microsoft.com/).