Hey no problem, if you have an Ubuntu box running on slicehost etc. you can follow the following to setup postfix: https://help.ubuntu.com/community/Postfix

In terms of sending the mail, you'll need some kind of simple app to talk to the smtp server, for example a rails app that uses ActiveMailer. If you're familiar with rails, this will help: http://api.rubyonrails.org/classes/ActionMailer/Base.html

Though there are probably even simpler services that can talk to SMTP servers even better, as rails is sort of a lot of overhead just for actionmailer.

Hope that helps!