[colug-432] smtp filters

[Rob Stampfli]

On Mon, Apr 22, 2013 at 09:36:04AM -0400, Scott Merrill wrote:
> I've been kicking around the idea of migrating my email off of Google
> Apps. I'd lose a fair bit of integrated functionality on which I've
> come to rely, I realize, but I think there may be some long-term
> benefits to being responsible for my own communications.

I use sendmail as the MTA for my cboh.org domain, since that's what
I've always used and know my way around.  Postfix is probably a similar
setup.  I have two MX addresses, homed to virtual servers for the
cboh.org domain.  When a message is received for me, it is forwarded
to a local MTA on my local LAN.  The forwarding is done on an unusual
port and relies on my local external IP address not being vary labile,
but that has not been a problem here since I switched to WOW, even
though it is nominally a dynamic address.  (It did become a problem
with Insight -- long story -- and was the driving force behind my
switching providers.)  The LAN server's /var/mail directory is then
mounted on my local Linux boxes via NFS, or is directly accessible
via ssh/mutt.

I use a combination of greylisting, DNSBL, pre-greeting, and clamav on
the virtual servers.  Have toyed with the idea of adding something like
spamassassin, but never gotten around to studying it enough to understand
how to incorporate it.  Also, even if someone might devine the private
port number, the local server is further protected by rules that only let
it respond to the IP addresses of my external servers.

On the whole, it works well, but it does come with a significant amount
of administrative overhead.  I'm fairly sure, though, that no one is
reading my emails over my shoulder.

Scott, if you have any interest in what I'm doing, or would like to see
how all of this is achieved in a sendmail configuration, feel free to
contact me off-line.

Rob