status=deferred (temporary failure) using ldap and 2 virtuals domains

Hi Zhang;

First, here is the configuration of my servers:
A central ldap server (ldap iredmail) manages two domains : domain.tld and zz.domain.tld.
An e-mail server (iredmail) manage  domain.tld and connected to remote server ldap
An e-mail server (iredmail) manage zz.domain.tld and connected to remote server ldap

I can send emails from these two mail servers to gmail, yahoo, etc. ..

But when I send an email from domain.tld zz.domain.tld  or from zz.domain.tld to domain.tld , I get the following error:

status = deferred (temporary failure) in the mail.log file

So i can't send emails between the  twho  mail serveurs

Please help me because the 2 servers are on line.

Thank's for help

==== Required information ====
- iRedMail version:
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):
- Linux/BSD distribution name and version:
- Related log if you're reporting an issue:
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