[OpenIndiana-discuss] sendmail simple setup home lan

[Oscar del Rio]

On 24/05/2014 4:27 AM, cpforum wrote:
> Yes if you choose dovecot as an IMAP server it's better to use dovecot local delivery agent.
>
> Related conf in M4 cf file
> FEATURE(`local_procmail', `/usr/local/libexec/dovecot/dovecot-lda',`/usr/local/libexec/dovecot/dovecot-lda -d $u')

Or Dovecot's LMTP service, which is more efficient than LDA
http://wiki2.dovecot.org/LMTP

FEATURE(`local_lmtp', `[IPC]', `FILE /var/run/dovecot/lmtp')
MODIFY_MAILER_FLAGS(`LOCAL', `-P')

>> Something I like about using Solaris or Solaris-based OS as mail server
>> is that you can save a lot of space by just turning on ZFS compression,
>> since email messages compress well, especially with ZFS gzip compression.
>>
> It's probably a good idea for mail with big files attached, but I have a doubt for small messages (file smaller than
> minimal allocation block size (UFS default was 8K/1K. ZFS blocksize is probably the same order).

I use Dovecot with "mdbox" mailbox format which stores several messages 
in a single file, with multiple files per mailbox.
http://wiki2.dovecot.org/MailboxFormat/dbox
This prevents having thousands of tiny files (Maildir) or single huge 
files (mbox)
The mdbox files compress well (ZFS gzip compress ratio 3.2x in our mail 
spool)

> Deduplication would be a better solution when big messages are sent to several users. To be effective it needs to store big
> attachements as separate files so that ZFS recognize duplicate. Then we need to have and improved Maildir storage scheme
> able to split a mail with attachements in several files instead one.

Another powerful feature of Dovecot's mdbox is automatic deduplication 
of attachments, a.k.a single-instance-storage.  When enabled, Dovecot 
saves the attachments on separate storage and uses the MD5 sum of the 
attachments to determine if it is a duplicate, even if it is on 
different folders (e.g. Inbox + Sent) or multiple users. No need for ZFS 
deduplication.

The attachment storage does not compress as well as the mailbox storage 
(attachment storage ZFS compression on our server: 1.2x) but this 
storage can be sent to separate disks or to NFS servers.

Another feature of mdbox is that old emails can also be moved to 
alternate storage transparently to the user. If you are running out of 
space in the mail spool, move everyone's old emails to another storage 
instead of nagging users to clean up. Or run a cron script to move 
emails older than X months to the alternate storage. The users will not 
notice any difference.

We use fast drives for the main mail spool, and cheaper larger drives 
and NFS servers for old-mail and attachment storage.