Sending mail from 1C, and reject_non_fqdn_hostname?

Question

postfix

Hello. The enterprise has a Centos7 mail server based on Postfix + Dovecot and of course a domain, 50 pieces of user mailboxes. Everything works great. In the same network there is a screw server on which there is a 1C server and which is not included in any domain. For 1C, an account is set up on the mail server, all settings are registered. 1C sends reports by email to the director on the mailbox that is on the mail server, and when sending mail on the mail server it is represented by the name of the Windows machine, in my case it is MAIN and naturally immediately receives a reject_non_fqdn_hostname. I'm not going to remove this reject, after all it's a standard in rejects. How to let this windows machine send mail without unnecessary checks, or solve this problem in another way?