Send e-mail error only to one domain!!!!!

[iovo]

Helli,
i've strange problem and i can not fix it. I can send e-mail with no problem, but only one domain return this error:
Helo command rejected: Host not found (in reply to RCPT TO command))
here is all error message:

postqueue -p

06C6F17B7B 894 Mon Nov 6 23:06:25 iovo@xxxxx.com
(host mx1.mail.bg[193.201.172.114] said: 450 4.7.1 <maria.site.com>: Helo command rejected: Host not found (in reply to RCPT TO command))
batevanko122322@mail.bg


iovo@xxxxx.com is my e-mail
<maria.site.com>: is my server

[till]

Please check with the command dig or nslookup that the DNS records for the domains:

xxxxx.com

and

maria.site.com

are existing.

[iovo]

Please check with the command dig or nslookup that the DNS records for the domains:

xxxxx.com

and

maria.site.com

are existing.

I've problem with DNS record and i fix it up.

Thank You for your help, till :D