Postfix rejects mail for local user

Hi guys!
I would like to ask your help about Postfix configuration. I'm confused about local user settings.

I setted up my mail server with Postfix and I followed this guide: https://geekpeek.net/postfix-with-dovecot/. I already used for years and it was always good.

Here my server configuration details:
- My FQDN is: myserver.mydomain.com
- My domanin is: mydomain.com
- My virtual_mailbox_domains file contains: mydomain.com, mydomain.net, mydomain.it

I send and receive mail from all domain listed in virtual mailbox, but I receive error "550 5.1.1 : Recipient address rejected: User unknown in local recipient table" if I try to send/receive any message to/from any address related to FQDN myserver.mydomain.com.

I read that as of Postfix version 2.0, the Postfix SMTP server rejects mail for unknown recipients in local domains (domains that match $mydestination or the IP addresses in $inet_interfaces or $proxy_interfaces) with "User unknown in local recipient table". Here the link: https://www.postfix.org/LOCAL_RECIPIENT_README.html. So I need to define local address related to my FDQN? If so, do you have any example?

Thank you for your support! Best regards