General question about alias domains

==== Required information ====
- iRedMail version: 0.8.7
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): LDAP
- Linux/BSD distribution name and version: RH 6.6
- Related log if you're reporting an issue:
====
Hello,
I have general question about alias domains.
I've seen article http://www.iredmail.org/docs/ldap.add.mail.alias.html and I know it will probably meet all my requirements.
The only question is:
If I have domains example1.com example2.com example3.com
Can user use all email addresses (user@example1.com. user@example2.com, user@example3.com)  to log in to services (webmail pop3 etc)