Getting "553 Relaying disallowed as xxx@site.com"

Getting "553 Relaying disallowed as xxx@site.com"

Hello, I sat postfix on my server to work with zoho smtp, all records are pointing correctly.

So I set postfix to use eg info@mydomain.com

this email is part of the group support@mydomain.com

My contact form is trying to send from support@mydomain.com but I'm getting the error:

Final-Recipient: rfc822; xxxxxxxxx@xxx.com
Original-Recipient: rfc822;xxxxxxxxx@xxx.com
Action: failed
Status: 5.0.0
Remote-MTA: dns; smtp.zoho.com
Diagnostic-Code: smtp; 553 Relaying disallowed as support@mydomain.com

Also note that both emails info@mydomain.com and support@mydomain.com are in the Send Mail As section.