[Maybe OT] SMTP mailer and authenticated use

[Paul Howarth]

mike at pelleys.com wrote:
> Folks - I'm not sure if this is really on topic, but here's my problem.  I
> currently run my own mail server from home and, of course, I have no
> issues with providing anti-spam, anti-relaying, etc.  However, my ISP is
> probably going to switch me to a port-restricted PPPoE DSL connection. 
> Thus, I'm not going to be able to run mail mail server.
> 
> I do have the ability to put my server in a friend's server room but how
> do I ensure that only "my" computers have the ability use the SMTP Postfix
> server to send mail?  I mean, the server has to be able to receive
> legitimate SMTP mail, but I don't want anyone else to be able to relay
> from my server.  Since I will have a *very* dynamic (apparently) IP
> address, I can't use the IP address restrictions within the main.cf to
> address what IPs can use the server to relay.  I thought about SMTP SASL
> authentication but it seems to me (please correct me if I'm wrong) that
> this will block legitimate incoming mail to myself - won't it?
> 
> Anyway, if anyone has suggestions or point me to the right resouce, it
> would be greatly appreciated!

SASL is the right way to go. I don't know how to do this in Postfix as I'm a 
sendmail user myself, but the gist of it is that SASL is used to control who 
can relay mail; it should have no effect on mail delivery to "local" domains, 
i.e. your own, which will not require authentication as there is no relaying 
involved - the mail is to be delivered locally, not relayed elsewhere.

Paul.