SSL Certificate integration

==== Required information ====
- iRedMail version: 0.8.5
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):  MySQL
- Linux/BSD distribution name and version:  Ubuntu 12.04 LTS
- Related log if you're reporting an issue:
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May I know how could i change the self-signed SSL certificate to one that is properly signed from GoDaddy?

Moreover, I always receive the notification of "The Target Principal Name Is Incorrect" from Microsoft outlook when I try to connect to my own server, is there any way to solve the problem without replacing the self-signed certificate with a proper signed one?

Thanks a lot.