mail quota exceeded notification

Hello everyone!
Sorry if this question was asked.
Discovered an unpleasant phenomenon. When the mail quota is exceeded, a notification letter comes only in one mailbox. Although, as it turned out, the quota was exceeded for many. Is this a mistake or is it supposed to be?
I would also very much like to have a setting in which a notification about reaching a certain limit of cats would be sent to the culprit in the box.
Now this is done using dovecot, but the letter is sent only once and the user often does not take action.
Thank you.

Code:

root@mail:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Debian
Description:    Debian GNU/Linux 9.13 (stretch)
Release:        9.13
Codename:       stretch

Code:

root@mail:~$ php -v
PHP 7.0.33-0+deb9u10 (cli) (built: Oct  6 2020 17:08:28) ( NTS )
Copyright (c) 1997-2017 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2017 Zend Technologies
    with Zend OPcache v7.0.33-0+deb9u10, Copyright (c) 1999-2017, by Zend Technologies

Thank you.
I have been using ISPconfig for over 5 years now. Really like. Thanks for your hard work!

 

What have you configured in ISPConfig Panel | System | Server Config | Mail |
in the "Send quota ..." settings?
More info in ISPConfig Manual.

 

Mailbox quota statistics - yes
Send quota warnings to admin - yes
Send quota warnings to client - yes
Send quota warning each X days - 1 day
Send quota ok message to client - yes

 

Maybe this is important.
I don't have a single client. I only use ISPConfig as my mail server.

 

How have you verified the quota notice is sent only once?

 

Checked on a test mailbox.
/etc/dovecot/dovecot.conf

Code:

...
plugin {
  quota = dict:user::file:/var/vmail/%d/%n/.quotausage

  # no longer needed, as 'sieve' is in userdb extra fields:
  sieve=/var/vmail/%d/%n/.sieve

  sieve_before=/var/vmail/%d/%n/.ispconfig-before.sieve
  sieve_after=/var/vmail/%d/%n/.ispconfig.sieve
  sieve_max_script_size = 2M
  sieve_max_actions = 100
  sieve_max_redirects = 25
  quota_warning = storage=95%% quota-warning 95 %u
  quota_warning2 = storage=90%% quota-warning 90 %u
}
service quota-warning {
  executable = script /usr/local/bin/quota-warning.sh
  user = vmail
  unix_listener quota-warning {
  user = vmail
  }
}
...

Messages from dovecot are only sent when crossing the 90% and 95% threshold