==== Required information ====
- iRedMail version (check /etc/iredmail-release): 0.9.2
- Linux/BSD distribution name and version: Ubuntu 14.04 LTS
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx): both
- Manage mail accounts with iRedAdmin-Pro? Yes
- Related log if you're reporting an issue:
====

Hi,

Could iRedMail go further in folder unification and include additional alias in the default configuration? Checking dovecot configuration I noticed few thing... first, commit  97e26f4 already took care of 'Sent Messages' for 'Sent', 'Spam' for 'Junk' and that's good but the default configuration is missing the 'Sent Items' and few others (which I would like to be included if possible at all). Let's look at the default configuration:

# dovecot.conf
...
namespace {
   ...
    mailbox Sent {
        auto = subscribe
        special_use = \Sent
    }
    # This is an alias mailbox for "Sent".
    # Reference: http://wiki2.dovecot.org/MailboxSettings
    mailbox "Sent Messages" {
        auto = no
        special_use = \Sent
    }
   ...

Unless I missed it (dovecot -n didn't list it either) 'Sent Items' is missing in the mailbox settings:

...
 mailbox "Sent Items" {
        auto = no
        special_use = \Sent
    }
...

Also, maybe 'Sent Messages' should be considered? Looking at Mail App and Outlook, perhaps it will be useful to unify all the mess created by different clients:

...
 mailbox "Sent Items" {
        auto = no
        special_use = \Sent
    }

 mailbox "Sent Messages" {
        auto = no
        special_use = \Sent
    }

 mailbox "Junk E-mail" {
        auto = no
        special_use = \Junk
    }

 mailbox "Deleted Messages" {
        auto = no
        special_use = \Trash
    }
...

Also I fail to understand why it needs to assign SPECIAL-USE as well as mailbox alias definition but there must be a reason. Is it to prevent the mailbox from being subscribed specifically?

...
    mailbox_alias_old = Sent
    mailbox_alias_new = Sent Messages
    mailbox_alias_old2 = Sent
    mailbox_alias_new2 = Sent Items
...
    mailbox Sent {
        auto = subscribe
        special_use = \Sent
    }

    mailbox "Sent Messages" {
        auto = no
        special_use = \Sent
    }
   ...

Other considerations:

Archives => Thunderbird
Templates => Thunderbird

Pine/Alpine uses "sent-mail"