On the email filter, if you need to pipe the email to another program (like another mail filter like procmail or scanner like clamav), you cant set commandline options.

Steps to reproduce:

Click
Edit -> Message filters -> New

At the filter rules pannel select:
* Send to a program (pipe)
* Select the program on the browser window
* Select some program return action
* Input some return value

What is missing is the option to set the commandline parameters for the piped program.