Can you elaborate how to check it?
the content of the file is:
# Authentication for passwd-file users. Included from 10-auth.conf.
#
# passwd-like file with specified location.
# <doc/wiki/AuthDatabase.PasswdFile.txt>
passdb {
driver = passwd-file
args = scheme=CRYPT username_format=%u /etc/dovecot/users
}
userdb {
driver = passwd-file
args = username_format=%u /etc/dovecot/users
# Default fields that can be overridden by passwd-file
#default_fields = quota_rule=*:storage=1G
# Override fields from passwd-file
#override_fields = home=/home/virtual/%u
}
I’m trying to look at
/etc/dovecot/users
but there it’s not exist.
furthermore those are the permisssions for the directory of /etc/dovecot:
drwxr-xr-x 4 root root 4096 Jul 23 18:33 .
drwxr-xr-x 111 root root 12288 Jul 23 18:33 ..
lrwxrwxrwx 1 root root 49 Jul 23 19:53 cert.pem -> /etc/letsencrypt/live/meta-read.com/fullchain.pem
drwxr-xr-x 2 root root 4096 Jul 23 11:27 conf.d
-rw-r--r-- 1 root root 4711 Jul 23 17:51 dovecot.conf
-rw-r--r-- 1 root root 1024 Jul 23 18:33 .dovecot.conf.swp
-rw-r----- 1 root dovecot 1507 Jul 23 18:33 dovecot-dict-auth.conf.ext
-rw-r----- 1 root dovecot 852 Jul 23 18:33 dovecot-dict-sql.conf.ext
-rw-r----- 1 root dovecot 5824 Jul 23 18:33 dovecot-sql.conf.ext
lrwxrwxrwx 1 root root 47 Jul 23 19:53 key.pem -> /etc/letsencrypt/live/meta-read.com/privkey.pem
drwx------ 2 root root 4096 Jul 23 18:33 private
I’ll like to mention that also when I try to connect with other client such as Thunderbird I get error message of probably wrong configuration/username or password. 
