IMAP mail for heavy users
The question of having mail solutions that scale to many users is often
discussed, I have a variation.
I am setting up a Mail Server for our company, with users distributed,
some of them on slow dial-ups. Total number of users is under 50, in 3
domains. My current method is using Jeremy Reed's patched gnu-pop3d for
virtual addresses, and exim. I also offer users IMP (horde) to read
mail while travelling.
Because users often have multiple machines (one in Singapore, one in HK,
and a laptop), I set up aliases, eg: mail to ghane goes to ghane,
ghane-hk, and ghane-trav. I set up a POP account on each PC, and voila,
I can read mail from all places. Users are happy.
I am now thinking of switching to IMAP for users, mainly to help when
lines drop on slow connections (POP starts again from Message 1), and to
enable multiple PCs to view the mailbox on server. Added bonus: Sent
Mail is viewable from all locations too, stopping the practice of BCC:
me that users resort to. Virtual name@domain will deliver to a real
user, which the person reading logs in as, firstname.lastname@example.org -> abcxyz , so
IMAP support for Virtual domains is not required.
Other data: number of users, low, will not cross 100 anyway for another
couple of years. Usage patterns, heavy. Users think nothing of sending
3MB attachments. This scares me, as my experience is that a 100MB inbox
will slow startup considerably.
Hence pointers required:
Should I deliver to maildir? Will IMAP access be faster in this case,
with a few hudred mails and a few hunded MB?
I like exim, any reason not to use it?
I could deliver to MySQL, which is running on the box, I just don't
understand it, and I would like to stick to a known format when
something goes wrong.
What could users use to change their passwords, or vacation messages? I
persume they could use IMP to read and deply while travelling.
And finally: Is there any standard to sync or replicate address books?
Thanks a ton for reading this.
PS: Secondary MX available for "personal" domains, I have a LARGE spool
disk, and as long as you are up once in a while, I could even bump up
the life of mails in spool beyond 5d. Ditto Primary/Secondary DNS for
personal domains of list members.