Now I have working Postorius and I can subscribe myself to the test list and get the welcome message (with incorrect urls in it!).
But I could not post to the list or mail to the list owner from outside:
550 5.1.1 email@example.com: Recipient address rejected: User unknown in virtual alias table
I've checked postfix/main.cf and everything looks right in it. Also I've ensured that var/data/*.db files are world-readable. Selinux is disabled.
How could I debug this error?