I'm using ISPConfig3 on a Debian 8 server. I'm using Dovecot for mail delivery. My httpd is Apache2. I can create a .sieve file in the Maildir directory of the user, manually enter sieve rules, and they will be obeyed. When I attempt to create them with ISPConfig3, however, the sieve rules are not created and the file is not created. The file should be located at /var/vmail/%d/%n/.sieve, and manually creating this file and populating it with sieve rules has the result of Dovecot respecting those sieve rules on delivery of new mail. The mail_user table in the dbispconfig MySQL database has the /var/vmail/%d/%n directory set as maildir, and /var/vmail set as the homedir. I have ensured that the ispconfig user has write access to the /var/vmail/%d/%n directories, and I have tried manually editing the /usr/local/ispconfig/server/plugins-enabled/maildeliver_plugin.inc.php file to force ISPConfig3 to set the sieve_file variable as /tmp/file.sieve, but that file also does not get created by ISPConfig3 when I save custom mail rules. I have ensured that all mail-related plugins are enabled: /usr/local/ispconfig/server/plugins-enabled# ln -s /usr/local/ispconfig/server/plugins-available/maildeliver_plugin.inc.php maildeliver_plugin.inc.php /usr/local/ispconfig/server/plugins-enabled# ln -s /usr/local/ispconfig/server/plugins-available/mailman_plugin.inc.php mailman_plugin.inc.php /usr/local/ispconfig/server/plugins-enabled# ln -s /usr/local/ispconfig/server/plugins-available/mail_plugin.inc.php mail_plugin.inc.php /usr/local/ispconfig/server/plugins-enabled# ln -s /usr/local/ispconfig/server/plugins-available/maildrop_plugin.inc.php maildrop_plugin.inc.php /usr/local/ispconfig/server/plugins-enabled# ln -s /usr/local/ispconfig/server/plugins-available/getmail_plugin.inc.php getmail_plugin.inc.php I do see the lines for the changes that I am making in the web frontend of ISPConfig3 in the sys_datalog table of the dbispconfig database, but I do not see them show up in any of the log files in /var/log/ispconfig, even after setting logging to verbose.