RE: Setting up a mail server
> Many of these user accounts will no doubt be sending and
> receiving email
> from dial-up accounts, which limits the ability to deny service on a
> per-IP basis. Suggestions for security, with pointers, please? I
> already plan on SSL, I'm asking I guess more about open relay
> issues in
> this sort of setup. Also, these user accounts will not be
> dialing into
> an ISP that I control, but I may wish to allow them to use me as a
> smarthost - does this seem foolish? I am undecided.
You could try to setup "pop-before-smtp". (apt-get install pop-before-smtp)
Any IP address trying to use your SMTP services for relaying will have to
have authenticated through POP (or IMAP) a few seconds before.
I know some ISPs use that, its not too much restrictive for users, since
they can still use plain SMTP, not ESMTP.
Hope this helps