Settings smtp port in linode

- iRedMail version: iRedMail-0.8.6
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Linux/BSD distribution name and version: Ubuntu 13.10 (GNU/Linux 3.12.6-x86_64-linode36 x86_64)
- Related log if you're reporting an issue: http://paste.ubuntu.com/6790978/

Hello, I need to properly configure all guidelines of $ smtp variable.
I'm using default settings and do not know which value goes to "host".
When I installed the iredadmin linode server, configured the hostname to be "demo.tosystems.net" even putting this in "host" can not send emails via PHP.

I would like a help from you.
I am very grateful.