Authenticated SMTP

[Wayne Pascoe]

Hi all,

I need to provide an SMTP service to someone who travels around thie
world. I can't do this with a specific IP address, as they use a variety
of ISP's in different locations.

To this end, I'd like to setup authenticated SMTP, preferably using
postfix. 

I've had a look in the postfix faq and it was a bit vague on this point.
In merely said that you need to force the user to authenticate against a
pop server first, that maintains a postfix compatible access table.

Can anyone point me to a document that explains what pop servers might
be suitable for this task and how to go about setting up this
authentication ? 

Regards,

-- 
Wayne Pascoe