subdomain mail receive problem

==== Required information ====
- iRedMail version: 0.8.6
- MySQL
- FreeBSD 10 64bit
====

Hi,
I have 2 main domain, maindomain.com (works well), otherdomain.com (works well) and subdomain.othetdoamin.com (sent works well) but I can't receive mail from some other people (gmail works well).
I think problem is in relay, because, when i sent mail to user@subdomain.othetdomain.com mail is deliver to user@otherdomain.com but not to user@subdomain.otherdomain.com.
From google mail nad my server work well, but some other people not.

Please help me.

Best regards
Michal