How to connect to postfix + dovecot + Ubuntu 18.04 + MySQL mail?

Question

Dovecot

There is a droplet on DigitalOcean with a server and one site, but the site had to do mail.
I made it according to a cheat sheet from DigitalOcean, which is just awfully detailed and with examples of the correct configuration files - here
Everything seems to be fine, but the mailer does not connect with a complaint about the password, and there is such beauty in the logs

dovecot: imap-login: Disconnected (auth failed, 6 attempts in 38 secs): user=<office>, method=PLAIN.......

At first I did not want to contact the database, but I found # in the password and changed the password. Now I don't even know which way to look.
Dovecot works, restarts and does not complain about anything, and the mail cannot be received / sent.
And mail programs approve all settings until it reaches the login/password
. What could be the snag? Where to dig?
It is possible somehow boxes with passwords without frills with MySQL?
Or the command itself is not correct and because of the "wrong" hash format and passwords are not recognized?

INSERT INTO `servermail`.`virtual_users`
(`id`, `domain_id`, `password` , `email`)
VALUES
('1', '1', ENCRYPT('firstpassword', CONCAT('$6$', SUBSTRING(SHA(RAND()), -16))), '[email protected]'),
('2', '1', ENCRYPT('secondpassword', CONCAT('$6$', SUBSTRING(SHA(RAND()), -16))), '[email protected]');

Answer 1

Closed/Solved Apparently
, something was overlooked somewhere and the complete removal of mail programs with their settings and careful installation/configuration helped and everything works...
spam is flying ... I'll probably also delete it and reconfigure it using the new opendkim