filtering email

[Tom Allison]

I have a question that might be more about sieve than cyrus, but 
hopefully they are related enough that I can get away with this question.

:)

procmail has the ability to "shell out" and run other commands as needed 
on the basis of the email content.
I can use certain filtering criterial to initiate an external program.

Can you do anything like this under sieve/cyrus-imap?

sieve, as I understand it, is an application which is "sandboxed" and 
not capable of being used to shell out to another application.

At this point, it seems my only option to to attempt sticking procmail 
in the middle of the delivery process.
It's a bit of a slow down, but there might not be a choice in the matter....

thoughts?