How to allow remote IP for Relaying?

Hello,

I need urgent help of you. Hope you will help me to solve it.
I have installed Postfix with Smarthost (Relaying) on remote server, when I send email, i get the this message (550 relay not permitted (in reply to RCPT TO command)). How can I allow the remote IP address in Hestiacp for Relaying? Thanks in advance.