Well I'm still exploring my options.
Neomail seems to be a quite reasonable Webmail program which will read one's mail from a local mail spool. I hav installed it and it's nearly working but I seem to have an issue with the perl installation at the moment. I'm waiting for my subscription to the Neomail list to become live to ask a question about it.
I'm also playing on my home system. I now remember why I have previously steered away from using IMAP4, the problem is that each MUA seems to have its own view of how IMAP4 should work such that it's
well nigh impossible to use an IMAP4 server with different MUAs.
It turns out that the remote system where I read my mail by ssh'ing in with mutt runs an IMAP4 server, it looks like it's the same one as I have on my Slackware 9.1 system at home. I can't work out what IMAP4 server it is as the manual page doesn't tell you. I got my home one working just now by simply uncommenting the line in /etc/inetd.conf and kicking inet.
Using mutt I can access all my mail perfectly, down through quite a deep hierarchy of folders, currently maildirs. This works the same from localhost and the remote system.
Mozilla mail fails miserably to access the same mail, it allows me to login to the IMAP server and displays the top level folder of the hierarchy and that's it, no mail messages are visible at all. It also creates a non-existent mailbox/folder called inbox
Balsa is just disastrous, it does say it's still experimental and that's the way it looks.