RE: Setting up a mail server

[DEFFONTAINES Vincent <Vincent.DEFFONTAINES@coe.int>]

> 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

Vincent