email does not arrive at the destination.

==== Required information ====
- iRedMail version: 0.8.7
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Linux/BSD distribution name and version: Debian 7
- Related log if you're reporting an issue:
====
Managed to install iRedMail normally. No error messages. I can access both the control to create domains and users, as a User Inbox.
The problem is that no messages I send comes up to the recipient. Messages also sent to the accounts created in iRedMail also not arrive.
I'm using the firewall rules suggested by the installation of iRedMail.
The SMTP traffic are not blocked on my server, that accessing the internet normally.
Please thank all who can collaborate.