I have some users (a@domain.com, b@domain.com) which a part of a given mail list, let's call it list@domain.com. I want to allow them to send mails from this mail list address instead of their own email address, so that the response will be send to the mail list and not only to the user himself.
I can change the mail address in my mail client to the one of the mail list, but the server will reject the mail, since it is not a valid mail account. Of course I can add the default reply adress in the mail clients, but that's not what I want. Is there any possibility to achieve this?

Thanks a lot!

==== Required information ====
- iRedMail version: 2.0
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): LDAP
- Linux/BSD distribution name and version: ubuntu 12.04
- Related log if you're reporting an issue:
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