Restrict Incoming Mail

[Steve Swaney]

> -----Original Message-----
> From: MailScanner mailing list [mailto:MAILSCANNER at JISCMAIL.AC.UK] On
> Behalf Of Brendan Chard
> Sent: Thursday, October 28, 2004 12:03 PM
> To: MAILSCANNER at JISCMAIL.AC.UK
> Subject: Restrict Incoming Mail
>
> This is more of a post installation, big picture question but hopefully
> some
> of you have done this.
>
> I now have a FreeBSD box up and running with MS that is serving as a mail
> relay for 4 other FreeBSD boxes that actually have the user accounts on
> them.
>
> How can I restrict the FreeBSD boxes behind the mail relay server to only
> accept incoming mail from the MS relay server and localhost?  Can this be
> done while still allowing the users to send mail out through the FreeBSD
> boxes that they log into?
>
> Thanks,
> -Brendan
> brendan at chard.net

First Method - Look at the MAQ. specifically:

        0.5 What if I want just a gateway that filters mail sends to
        my other (Exchange, Notes...) server
        (and block emails to unknown recipients)?

The exact methods will depend on which MTA you use but the basic idea is the
same.

1. Write scripts that create a map or DB of the users on the mail hubs. The
links in the MAQ describe a few way's to do this but your setup will
probably require custom scripts.

2. Modify your Mat to use this map to validate the recipient before
accepting the mail. Again the links in the MAQ describe a few way's to do
this.

I have a script that does this for one backend POP/IMAP server. Drop me a
line off list if you want a copy

Second Method- Milter-Ahead:

I tried testing this very quickly but couldn't get it to work with an
Exchange 2003 server on the back end, but the problem could have been that
since the mail was queued for MailScanner, milter-ahead  thought the user
was local. This is what the logs appeared to reflect.

This is a very promising method of blocking email at the gateway. It is dead
easy to install and configure.

Does anyone have this working with MailScanner?

Thanks,

Steve

Steve Swaney
President
Fortress Systems Ltd.
www.fsl.com
steve.swaney at fsl.com


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