It may seem surprising to some, but PINE is actually extremely well-suited to use on devices with touch screens, if you set its enable-mouse-in-xterm option so that it registers taps on the touch screen.
Although it can of course use traditional IMAP, it's configured here to use IMAP over SSH -- so that ssh-agent can keep the key and I don't need to enter a password or passphrase each time I start PINE. I've deliberately removed the key from ssh-agent in the first screenshot, to demonstrate the ssh-askpass program running under Maemo:
After logging in and double-tapping the 'Folder List' option which is highlighted but partially obscured in the above screenshot, you're taken to a folder tree, which you can navigate by double tapping on its entries. The menu items (Help, ParentDir, PrevFldr, etc.) at the bottom can be used simply by tapping on them:
Double-tapping on folders descends down into them as if they were directories; with the Dovecot IMAP server, all folders appear both as 'directories' and as real folders. To actually open the 'l-k' folder instead of attempting to descend into it, I tap the 'OTHER CMDS' menu option at the bottom left, then the '[View Fldr]' option to go to the folder:
In the folder index, I can use the cursor keys to scroll up or down, and double-tap on a mail to read it. I could also use the menu options to sort the mail folder differently or to search. Use the 'OTHER CMDS' option to scroll through the available commands, and remember that some of them may be disabled in the configuration -- you can enable them in your .pinerc.
Now I can hit the 'Reply' option at the right-hand side of the menu options to reply to the message. PINE will ask if I want to reply to all recipients, and if I want to include the original message in my reply. I tap on the desired answers and I can then compose my message. When I'm done, I can send it by tapping on the 'Send' option...
For an ancient text-mode program, PINE is actually quite nice to use on a handheld device. It might be worth getting to know it and configuring it to your liking on a real computer though, rather than only on the Nokia 770. You can download it from ftp://ftp.infradead.org/pub/maemo/