Mail server with postfix and dovecot, incoming mails does not work...

Hello, my incoming mail does not work even if I have postfix and dovecot set correctly. It was working without problems and suddenly it doesn’t work. I have this in the log, what is it?
Apr 02 12:43:11 auth: Debug: client passdb out: FAIL 11 [email protected]
Apr 02 12:43:09 auth: Debug: auth([email protected],194.169.175.10): Auth request finished
Apr 02 12:43:09 auth: Debug: sql([email protected],194.169.175.10): Finished passdb lookup
Apr 02 12:43:09 auth-worker(31679): Debug: conn unix:auth-worker (pid=24864,uid=128): auth-worker<46>: Finished: user_unknown
Apr 02 12:43:09 auth-worker(31679): Debug: conn unix:auth-worker (pid=24864,uid=128): auth-worker<46>: sql([email protected],194.169.175.10 ): Finished passdb lookup
Apr 02 12:43:09 auth-worker(31679): Info: conn unix:auth-worker (pid=24864,uid=128): auth-worker<46>: sql([email protected],194.169.175.10 ): unknown user
Apr 02 12:43:09 auth-worker(31679): Debug: mysql(localhost): Finished query ‘SELECT username AS user,password FROM mailbox WHERE username = ‘[email protected]’ AND active=‘1’’ in 0 msec
Apr 02 12:43:09 auth-worker(31679): Debug: conn unix:auth-worker (pid=24864,uid=128): auth-worker<46>: sql([email protected],194.169.175.10 ): query: SELECT username AS user,password FROM mailbox WHERE username = ‘[email protected]’ AND active=‘1’
Apr 02 12:43:09 auth-worker(31679): Debug: conn unix:auth-worker (pid=24864,uid=128): auth-worker<46>: sql([email protected],194.169.175.10 ): Performing passdb lookup
Apr 02 12:43:09 auth-worker(31679): Debug: conn unix:auth-worker (pid=24864,uid=128): auth-worker<46>: Handling PASSV request
Apr 02 12:43:09 auth: Debug: sql([email protected],194.169.175.10): Performing passdb lookup
Apr 02 12:43:09 auth: Debug: client in: CONT 11 MXEydzNlNHI= (previous base64 data may contain sensitive data)
Apr 02 12:43:03 auth: Debug: client passdb out: CONT 11 UGFzc3dvcmQ6
Apr 02 12:43:03 auth: Debug: client in: CONT 11 bWlkZ2V0QHdlYmxhbmQuZnVu (previous base64 data may contain sensitive data)

Hello Marian, welcome to the Forums!

Looking at the entry that says;

Apr 02 12:43:09 auth-worker(31679): Info: conn unix:auth-worker (pid=24864,uid=128): auth-worker<46>: sql([email protected],194.169.175.10 ): unknown user

It looks suspiciously like the SQL database component in dovecot is trying to query the database and it’s credentials are failing. i.e. it looks like it’s trying to connect to a SQL server at 194.169.175.10 using the username “[email protected]” (and a hidden password) and either the username and password are incorrect, there is no account with those credentials, or the server is not set to accept connections from the IP address you are using.

Possible (example) causes;

  • Your IP address has changed and the server has not been updated to accept connections from your new address
  • Your database username or password has changed
  • The SQL server has crashed and been restored without the correct user permissions

The looks rather like it’s a hosted service (?) , if you could provide a little background / details I might be able to narrow it down a little more … ?