IMAP server alternatives

[Nagy László]

 Hello,

I tried cyrus-imapd, but I'm unsatisfied. Their website was down for a 
day. Now it is up, but the pages were not updated after 2003. They had a 
majordomo list but it is not functioning. I found another mailing list 
but nobody answers. I do not see answer to my question in its 
documentation.

Are there any alternative IMAP servers that have good support (e.g. 
working mailing list, up-to-date documentation), and can share IMAP 
folders between users?

These are the ones I see:

bincimap -- only maildir, cannot share folders
courier -- uses the maildir format, and it says it support sharing 
folders with a special root level folder
cyrus-imapd -- I could not find support for this
dbmail-mysql -- AFAIK no folder sharing
dkimap -- ???
dovecot -- early stages of development, can I trust in this?
imap-uw -- only maildir, cannot share folders
py24-twistedMail -- Looks like this is only a collection of modules

I could use py24-twistedMail to create shared folders, but this requires 
re-inventing the weel.
What do you recommend? Is courier the only alternative?

Thanks,

  Laszlo