[Dovecot] Newbee, some questions

[Thomas Harold]

On 11/22/2009 12:39 PM, Spyros Tsiolis wrote:
>
> 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.
>

We used Postfix only for a long time (SMTP/POP3), back in '07 I started 
researching, built a test rig in early '08 and we switched full over to 
Postfix/Dovecot in late spring of '08.  You'll have a lot of reading 
ahead of you and I recommend registering a domain or two to use as a 
test bed on the new system before you start adding the real domains and 
repointing MX records at the new box.

> 1. Do multiple domain handling.

This can be done with virtual domains and users.  We found it easier to 
go with virtual users instead of system users for our multi-domain setup.

http://wiki.dovecot.org/VirtualUsers
http://wiki.dovecot.org/SystemUsers

Personally, we use PostfixAdmin (a web-based tool) along with its 
databases (in PostgreSQL) to store our virtual domains and to manage 
domains/accounts.  Our Postfix (which handles the SMTP side) and Dovecot 
(which handles the POP3/IMAP side) query this database for domain/user 
information.

We used to use a system users setup, which had the advantage (and 
disadvantage) that Fred could receive email as "fred at AnyOfOurDomains" 
without having to do anything special.  With the virtual user setup, we 
had to put fred@ into one domain, and then setup aliases in the other 
domains that rewrote fred at otherdomain into fred at homedomain.  In the long 
run, I'm happier, because most of our users really didn't need to be 
addressable as "user at anyofourdomains".

> 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)

We store user email in Dovecot's Maildir setup, usually under:

/var/vmail/domain/user/

There are lots of sub-folders below that point specific to the MailDir 
implementation.  I personally have IMAP mailboxes with hundreds of 
thousands of messages spread across dozens of folders and a total size 
of over 2GB.

> 4. be able to do IMAP/POP3 and not SMTP/POP3 (or do I need all three
>     of them ?)

SMTP servers (postfix, sendmail) handle accepting mail from the outside 
world before handing it off to a LDA (local delivery agent) like 
Dovecot.  The SMTP server also handles taking mail from a mail client 
(submitted via SMTP) and either handing it to the LDA for local delivery 
or contacting foreign SMTP servers to deliver to other domains.

(Postfix also has an LDA component, and a POP3 component, but you can 
plug other LDA servers in like Dovecot.)

POP3/IMAP access to the mailbox location is usually the job of Dovecot.

> 5. Interface with things like web-based mail software (LAMP ?)

We use SquirrelMail here for our webmail.  I'm pretty sure that it talks 
to the Dovecot IMAP server in order to access the user's mailbox.  Once 
you have IMAP access to your mailboxes configured, you can use lots of 
different tools to talk to it.