Roaming email

I have a client with a problem.  A relatively simple problem that I can fix, but the fix is clumbsy and he doesn't like it. The result is him calling me every few days so I can re-explain the solution every time... I'm sick of it and there has to be a better way.

He has a laptop and he travels. The hotels he uses provide him with Internet access. The problem is with outgoing mail.

I don't know if this is common everywhere, but where we are the ISPs have started forcing customers to use the ISPs outgoing mail servers in an attempt to curb spam (I assume). So he needs to use a different SMTP server depending on where he is, ie:

at the office (with static IP so they allow private servers) he uses mail.hisdomain.com
at Hotel A he uses their ISP - smtp.telus.net
Hotel B uses a different ISP - mail.nc.shaw.com
Hotel C has a funky setup and uses - internalmail.localhost

Or whatever... So I told him that wherever he goes, he needs to find out the smtp requirements, open up his email program and change his settings... but remember to change them back when he gets back.

He's ok with finding the places' smtp server... but he just simply can't seem to remember how to change the settings on his email client, and he usually forgets to change them back when he's back in the office and he ALWAYS calls me to fix it!!!

So the solution I thought of, but I'm not entirely sure how to implement, is to have the email client settings permanently set to some ficticious address like supermail.bogusdomain.bob, and then have the HOSTS file setup to translate that address into the proper smtp server for the location he is in.  I'd like to setup some little program so that he just picks the "zone" he's in, and it rewrites the HOSTS file accordingly. And When he's in a new place, he just clicks "Add a zone" and enters the new smtp server.

But then I thought... hmm... maybe there is already something like this out there.  And that's what brings me here.  Anyone seen anything that solves my dilema without me having to write a program?

Thanks.