not able to receive mail

==== Required information ====
- iRedMail version: IredMail 0.9.0
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):  MySQL
- Web server (Apache or Nginx): Apache
- Linux/BSD distribution name and version:  Ubuntu 14.04 LTS
- Related log if you're reporting an issue:
====

Hi Team,

We can send the mail to any domain and it’s working but We are not able to receive the mail from some domain.

Just like :-
•         If we send the mail from GMAIL / YAHOO that time we got the mail but very late.
•         If we send the mail from other domain that time Delivery Failed.

So can you please let me know if any settings required.