[Dovecot] Newbee, some questions

[Spyros Tsiolis]

Hello list,

OK, I just registered with the list, so please be tolerant :-)
I've been using another MTA for about, oh, I'd say nine years now.

Due to reasons beyond me (mainly my clients demanding more for their
buck / things like webmail etc.), I was forced to start searching for
(always) open source alternatives. 

The last MTA was only POP3/SMTP. It does no webmail. It interfaces with
other software with a lot of pain and difficulty.

I'll cut to the chase. I would like to start using some kind of software
that can do the following :

1. Do multiple domain handling.
2. Have a centralized user base
3. Have a centralized mail repository for each user (like exchange, 
   only without the admin/maintenance pain that comes with it)
4. be able to do IMAP/POP3 and not SMTP/POP3 (or do I need all three
   of them ?)
5. Interface with things like web-based mail software (LAMP ?)

Am I in the right place ? I would certainly like to think so.
However, the feedback belongs to you .

Thank you kindly for your hospitality and patience,

S. Tsiolis