CentOS - Jun 2005 - Postfix / Postini question

I have a mail server that handles several domains.  One of these domains has
decided to use Postini.  For those not familiar with Postini, you set your MX
records to use their mail servers.  They filter mail, and deliver you only the
clean virus/spam free mail.  The idea is to only allow incoming mail from their
mail servers so spammers are unable to send to your mail server directly.  This
is fairly simple to do with standard restriction classes for a dedicated mail
server.  I am not sure how to accomplish this on a shared mail server.  Ideally
I would like to instruct postfix to accept mail from anywhere for all domains
except one domain (the one using Postini) and only allow mail destined for that
specific domain to originate from Postini's mail servers.  Any ideas would
be
greatly appreciated.

Thanks,
Barry

> -----Original Message-----
> From: centos-bounces at centos.org [mailto:centos-bounces at centos.org] On
> Behalf Of Barry Brimer
> Sent: Wednesday, June 29, 2005 9:47 AM
> To: centos at centos.org
> Subject: [CentOS] Postfix / Postini question
> 
> 
> 
> I have a mail server that handles several domains.  One of these
domains
> has
> decided to use Postini.  For those not familiar with Postini, you set
your
> MX
> records to use their mail servers.  They filter mail, and deliver you
only
> the
> clean virus/spam free mail.  The idea is to only allow incoming mail
from
> their
> mail servers so spammers are unable to send to your mail server
directly.
> This
> is fairly simple to do with standard restriction classes for a
dedicated
> mail
> server.  I am not sure how to accomplish this on a shared mail server.
> Ideally
> I would like to instruct postfix to accept mail from anywhere for all
> domains
> except one domain (the one using Postini) and only allow mail destined
for
> that
> specific domain to originate from Postini's mail servers.  Any ideas
would
> be
> greatly appreciated.

I'm not a postfix guru but I don't believe that is possible with a
shared server. However, it's been my experience that if your server is
not listed as an MX (and it won't), MXs exist (and they will --
Postini's) then mail will not be delivered to your machine by anyone
except Postini. The only two scenarios I am aware of in which mail would
get delivered to your server instead of Postini's would be if a) you
were listed as a fallback MX or b) no MX's were specified then the A
record for your domain would be used.

Have you looked through the postfix wiki, documentation, faq, mailing
list, etc? That'd be the first place I'd go since they _are_ the postfix
experts ;).

--
Marc

Barry Brimer wrote:
> 
> I have a mail server that handles several domains.  One of these domains
has
> decided to use Postini.  For those not familiar with Postini, you set your
MX
> records to use their mail servers.  They filter mail, and deliver you only
the
> clean virus/spam free mail.  The idea is to only allow incoming mail from
their
> mail servers so spammers are unable to send to your mail server directly. 
This
> is fairly simple to do with standard restriction classes for a dedicated
mail
> server.  I am not sure how to accomplish this on a shared mail server. 
Ideally
> I would like to instruct postfix to accept mail from anywhere for all
domains
> except one domain (the one using Postini) and only allow mail destined for
that
> specific domain to originate from Postini's mail servers.  Any ideas
would be
> greatly appreciated.
check_recipient_access
		key		value
		postini-domain	postini-domain-restrictions

smtpd-restrictions
	postini-domain-restrictions

postini-domain-restrictons
	check_client_access
		key			value
		postini-ips/rdns	OK
	check_client_access
		key			value
		anything(regex/pcre)	REJECT