You can run CEICW from SBS 2003 and select which attachments to be blocked. Or you can also make those same changes manually, per the instructions below:
1. Open Start, click Run, type %sbsprogramdir%\Networking in the Open box, and then press ENTER.
2. In the dialog box, find the SecAttsConfig.xml file, right-click the file and select Edit.
3. If you would like to allow the .vbs attachment (as an example), find the <Attachment Enabled=”True” Extension=”vb” Description=”VBScript file”/> sentence, change it to <Attachment Enabled=”False” Extension=”vb” Description=”VBScript file”/>.
NOTE: True = BLOCKED, False = ALLOWED
4. Click File in the menu, and then click Save to save the change to the SecAttsConfig.xml file.