Re: Restricting Incoming Email in Exchange by From Address

[Greg Jones <grjones () gmail com>]

Without explaining why, some of our employees require pop/imap access
to our exchange server from the Internet (they only need this for
receiving mail, and don't need smtp).   So when email from the
Internet comes in from a @mydomain.com address, I want to make sure
that whomever sent it is authenticated (using exchange), and reject
the traditional unauthenticated SMTP traffic when the From address is
a @mydomain.com address.  I will look at SPF more, but it seems to me
that what I'm trying to do should be pretty simple and effective.

Thanks

Greg

On 6/20/05, Steve <securityfocus () delahunty com> wrote:
> Not sure I follow on the first part.  Your users can connect to your
> Exchange server via other clients like POP? If so, turn off POP/IMAP.  For
> spoofing/phishing check out using reverse DNS lookups with Exchange and/or
> SPF.  That will improve your overall email security.
>
> STEVE
> ----- Original Message -----
> From: "Greg Jones" <grjones () gmail com>
> To: <security-basics () securityfocus com>
> Sent: Saturday, June 18, 2005 12:30 PM
> Subject: Restricting Incoming Email in Exchange by From Address
>
>
> In Exchange (any version), I would like to disallow email coming from
> the Internet (smtp) that has a From address of my domain.  This would
> force our employees to use OWA or Exchange (via VPN of course).  This
> would help with phishing and worms that are fooling some of our
> employees (e.g., emails from admin () mydomain com).  Is this possible?
>
>  Greg