Blocking spam based on from address

[Glenn Steen]

On 03/02/06, Kevin Miller <Kevin_Miller at ci.juneau.ak.us> wrote:
> Michael Masse wrote:
> > I'm using the latest release of MS and SA with sendmail 8.13 as the
> > MTA setup as a relay to a Groupwise system.    I'm having a big
> > problem with spam that bogusly claims to come from within my own
> > domain either via the envope sender or header sender or both.   SA
>
> Have you set up SPF?  That may help with some of that...
>
> ¨m no sendmail guru, but this is pretty easy to implement in Postfix  You do so with adequate sender restrictions (that check that the bozos don't use your addresses) and helo restrictions (again, check you get a fqdn or "literal IP address", and that neither are yours. Even if this might bend the letter of the RFCs it's OK (I'm to tired to remember what would be the point of allowing them to helo with your fqdn/ip). Only spammers/viruses do this.
I've been using such restrictions for quite some time now, no ill
effects. And combine that with just accepting mails destined to real
email addresses, and you¨ll be fine.
I can provide some examples (come monday) upon request.

--
-- Glenn
email: glenn < dot > steen < at > gmail < dot > com
work: glenn < dot > steen < at > ap1 < dot > se