Relay access denied

[pedromidiasf]

I'm configuring a new email and i'm getting this STMP message:
-  Relay access deniedts

220 xxxxxxxxxxxxxxxxxxx ESMTP Postfix
HELO yyyyyyyyyyyyyyyyyyyyyyy
250 ns348267.ip-37-187-253.eu
mail from: pedro@yyyyyyyyyyyyyyyyyyyyyyy
250 2.1.0 Ok
rcpt to:<pedro.ferreira@new_domain.com>
454 4.7.1 <pedro.ferreira@new_domain.com>: Relay access denied

The other domain works just fine (it's a primary domain), i tried to add a new primary domain with this domain but it's still the same.

Do you want me to share some files or configures? Please let me know

[Administrator]

you would need to provide more details explanation, probably the best would be to check on that with your server admin.