postfix or procmail

[cosme@esid.gecgr.co.cu]

Hi

All day I receive an email from external account user@external.com it
reaches a user of my local domain isabel@mydomain, need to automatically
be forwarded to other users on my domain and maria pepe.

I use Debian 6 and postfix 2.7

I tried aliases and postfix, also with procmail something like this

echo multiples: pepe maria >> /etc/aliases
postalias /etc/aliases

echo '/^From:.user@external\.com/i    REDIRECT multiples@mydomain.com' >>
/etc/posftix/encabezados

postmap /etc/postfix/encabezados >> /etc/postfix/main.cf


with procmail

:0 c
 * ^From.*user@external.com
 ! pepe@mydomain.com maria@mydomain.com

none of the 2 runs

How I can fix?

regards