How exactly to do this? Where to watch?

Please check the server logs to make sure that the connection is reaching the server and see what is the error message in the logs.

Thanks so much!

And I have a question, maybe you have a idea :

Every authentification failed with gmail when I add my mail. (mail dovecot: imap-login: Disconnected (auth failed, 1 attempts in 11 secs)

It says : “Login or password failed” while my login and password was good.

Do you have a idea of the problem ?

Thanks again.

Thank you for your attention, Sir,
It was an issue due to late hours and lost my focus on details after spending time on the wrong MD5 hash in the MySQL table.
SMTP issue was because of the wrong Thunderbird settings, (I changed the setting to try different auth options during the auth issue, then forget those setting on Thunderbird) it’s working properly now.
Also install SquirrelMail for web interface testing purpose, all fine.

Try to add this to your /etc/dovecot/dovecot.conf.

service stats {
unix_listener stats-reader {
user = vmail
group = vmail
mode = 0660
}

unix_listener stats-writer {
user = vmail
group = vmail
mode = 0660
}
}

Then restart dovecot.

We have a problem : Where we put the command : “echo test | sendmail test@exemple.org” we have a “Error: net_connect_unix(/run/dovecot/stats-writer) failed: Permission den))”.

Do you have a idea of the problem ?