Shared Mailbox?

[craig]

Hi,

I've been doing a lot of reading on this topic, I'm just finding a lot 
of doco that's potentially out of date now?

System:
Red Hat Enterprise Linux Server release 7.2 (Maipo)
dovecot-2.2.10-5.el7.x86_64

The need:
1. I'd like to create a mailbox called "accounts", email would simply 
get delivered to the account via "accounts at example.com" (Maildir format)
2. Share this mailbox so it appears in three other accounts as an extra 
folder called "accounts"
3. If a user reads an email in the "accounts" folder, I'd like the other 
users to know this.

Clients:
* Latest Thunderbird
* Outlook 2013.

Any advice welcome ;)

Cheers,

Craig