ladas at postfix configuration not work for my server: hosts=localhost at g-alias.cf and g-virt.cf I replaced it by hosts=127.0.0.1 (postfix say: cannot comunicate with mysql db) If someone know why, I will be glad to know. I get this advice here at forum.
This is due to the fact, that postfix runs in a jail and thus cannot access mysqld's socket. Running through a socket is way more efficient then having to spawn tcp connections all the time, so my suggestion would be to mount mysqld's run directory inside postfix's jail, by having this in /etc/fstab:
/run/mysqld /var/spool/postfix/run/mysqld bind defaults,bind 0 0
After reboot or after issueiung
postfix will succeed in accessing mysqld's socket.