[ale] Mail server config recommendations

[Jay Loden]

NOTE: I apologize if this is double-posted but for whatever reason I 
didn't see it post to the list so I'm sending it again in case it got lost.

Hi all,

I have been running my own mail server for a couple years and basically, 
I hacked it until it worked without really understanding much of what I 
was doing. I have Spamassassin filtering my incoming mail, and I've got 
sendmail working for sending and receiving mail. Lately a lot of SPAM 
has been getting through the SA filter, even after wiping the spam 
database and re-learning the spam from about 1500 recent spam emails.

What I'm looking for is recommendations (links, how-to guides, books are 
also appreciated) on:

1) reducing incoming SPAM through better tuning/use of SpamAssassin or 
another filtering system (not interested in blacklisting/RBLs or 
greylisting). I'm ok with using the Thunderbird spam filter here at home 
but that doesn't work on a mobile phone client, or when I use webmail or 
other clients, so I need something server-side.

2) Configuring sendmail (currently running 8.12.11) securely

3) Alternatives to sendmail, if recommended and any guides to 
configuration for the below (Postfix, perhaps?)

4) SMTP with some form of encrypted authentication (don't really know 
what the differences are between TLS or SSL or any other options) for users

5) Configuring POP and IMAP to use encrypted authentication so that my 
passwords aren't being sent in the clear (again, not sure what options 
are available there).

I realize this covers a lot of ground, but as I said, I'm just 
interested in tips and tricks, and of course recommendations based on 
your collective experience. I'm more than willing to do my homework and 
read suggested articles or books as well, so even if all you have to 
share is a useful tutorial url or a ISBN number, fire away!

Thanks,

-Jay