Procmail: how to forward messages without sendmail?

Hi all!

I'm using Postfix with Procmail and everything is working fine so far.
Now I'm trying to forward messages using the procmail's recipe:

:0 c
! newaccount@gmail.com

but I have a problem.
When the recipe is executed I get this error:

procmail: Executing "/usr/sbin/sendmail,-oi,newaccount"
/bin/sh: Can't open /usr/sbin/sendmail
procmail: Error while writing to "/usr/sbin/sendmail"
procmail: Non-zero exitcode (2) from "/usr/sbin/sendmail"
procmail: Assigning "LASTFOLDER=/usr/sbin/sendmail -oi
newaccount@gmail.com"

I don't understand why procmail is trying to use sendmail, when my MTA
is Postfix. Before installing Postfix, I have removed sendmail.

Thanks to everyone could help me.
CoolDB