[Sussex] Mail server recommendations?

[Mark Harrison]

OK, for various reasons, I'm ready to make the jump.

Can anyone recommend me a Linux mail server that does the following:

- Allows Outlook Express to read messages WITHOUT removing them from the
server (IMAP?)

- Has an HTTP/HTTPS client for when I'm at client sites where all I can use
is port 80/443

- Allows multiple users, with a mapping so that each user can have multiple
address ON MULTIPLE domains

.. ie Mark at ascentium.co.uk, Mark at startinvesting.co.uk go to the same
mailbox. Mary likewise has mail addresses on each. George only has a
startinvesting.co.uk one.

- Allows server-side rules so that mails from lists will be automatically
filed into appropriate subfolders. Ideally, these rules should be
configurable with the Outlook/OutlookExpress rules interface, but this part
of the requirement isn't hard - I'm quite happy to have some other engine
for setting server-side rules, since I'll probably re-subscribe to groups
with a "lists at ascentium.co.uk" address anyway :-)

- Is Free in both the money and OpenSource senses.

Regards,

Mark