Default postfix configuration error

The default latest V4 installation has problems with Postfix docker container. It incorrectly resolves its own domain.

Steps to reproduce:
1) Install fresh V4 on example.com with WordPress
2) Try to send an email from WordPress to test@example.com

Emails work to all domains except the same domain as web setup.

It starts with this error:
Jan 21 20:53:59 ip-xxxxxxxxx mydomain.com/smtpd[10882]: error: open database /etc/aliases.db: No such file or directory

When you go to email docker and create /etc/aliases file (even empty) it moves to this error:
Jan 24 12:19:59 ip-xxxxxxx website.com/smtpd[223]: NOQUEUE: reject: RCPT from websitecom_php_1.website.com[172.20.0.3]: 550 5.1.1 info@website.com: Recipient address rejected: User unknown in local recipient table; from=info@website.com to=info@website.com proto=SMTP helo=

Which makes me think that postfix has problems resolving the email and tries to send it to another container rather than to MX record.