One of the greatest things about the palm is it's ability for e-mail. I am constantly using my Palm for e-mail..... Literally everywhere! Anyway, there are a few e-mail clients around:

HandMail : Have been using this for a year. Not bad, but quite quirky. If you can get a free copy, then great, but don't buy it as Smartcode software are no more.

Eudora : Link Haven't used this much, although I am beginning to prefer this over HandMail. Easy to use and setup.

MarkSpace Mail : Link Good e-mail client. Very easy to setup, and good custom options. Love the ability to colour various e-mails / senders (see screen shot).

MultiMail SE : Link Comes with the newer palms and part of the internet pack. Good Layout, although looks a bit dated compared to newer apps

Mailer : Link Nice e-mail client. Integrates well with the address book (can do look ups of e-mail addresses). Colour support as well

ThinAirMail : Link Little WebClipping app that lets you access Hotmail.

Corsoft Aileron : Link E-mail app with support for attachments