Mbox Reader is a Qtopia program which lets you read mbox format mail files. That's all it does: it doesn't let you fetch mail messages from a server, reply to messages or delete messages from the file. It's designed to be operated entirely from the front panel buttons of the Zaurus: it isn't necessary to open the keyboard or take out the stylus.
There is a change log and you can download source and binary from here:
I wrote Mbox Reader so that I could read messages from a number of mailing lists on the train on the way to work. My mail is processed by procmail to split it into separate files for each mailing list. Every morning I drop my Zaurus into its cradle and the latest files are FTPed across to it.
The program is very simple to use. It can handle files with the MIME type text/mbox, which is installed along with the program. Such files are identified by the extension mbx. You can start the program from from the Applications tab, in which case a screen showing all available mbox files appears. Alternatively you can select a file with the text/mbox MIME type from the Documents tab.
Once a file has been selected a new screen opens to display a summary of all the messages in the file (subject, sender, date). You can use the cursor keys to move through the list and the SELECT button to open a message.
Mail messages are reformatted before display so that they fit the width of the screen. This usually makes the text more readable, but some forms of text (program code, poetry) may be harder to read so it's possible to turn off the reformatting. It's also possible to control the display of message headers.
Text which is quoted using standard conventions (leading '>') is displayed in italics. The colour of the text varies depending on the level of quoting: red, purple, blue and black for increasing numbers of '>'.
The Cancel button will always get you back to the previous screen, or shut down the application if you're on the file list screen.
Acknowledgement: I pinched the icon for Mbox Reader from KDE.