Email client recommendations?

[eluser]Wayne Smallman[/eluser]
Hi guys!

I know CodeIgniter has an email class built right in, but is there a Library (or the equiv.) for an actual email client?

I have a project which will need an email client and if there's something already out there — which I can build on top of an adapt for my own purposes — it'd help save time writing one from scratch.

Thanks!