header checks are not working

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header checks are not working
\ LDB (29 May 2007)
. \ Noel Jones (29 May 2007)
. . \ LDB (29 May 2007)
. . . \ Noel Jones (29 May 2007)

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Subject:	header checks are not working
Group:	Postfix-users
From:	LDB
Date:	29 May 2007

I am trying to allow only only users within a domain to send email to
all the users within the domain and not allow anyone outside the domain
to send email to the "sendall" list.

So, I have setup the following within header_checks,

if /^To: sendall@(|mailserver)(|\.)mydomain\.(com|org|net)/
!/^From: .*@(|mailserver)(|\.)mydomain\.(org|com|net)/ DISCARD Go away
endif

Any ideas???

Thanks,

LDB