Hello, Currently I am using other products like DirectAdmin, Plesk and cPanel. I don't have much experience with ISPconfig, so I bought the book (PDF:ISPConfig 3.1 Manual). I did read that Debian was supported, so I spun up a VPS and installed Debian 9 + ISPconfig 3.1.13. In the meantime I have my server running (s1.gigabitjes.nl). And I remembered that cPanel has this feature where I can compress the mail dirs. This saves quite some space as most data is just text. I would like to know if someone is actively using Zlib for Dovecot in production using ISPconfig. Is the correct method to add the required configuration in the folder [ /usr/local/ispconfig/server/conf-custom/mail ] ? I did read the details at [ wiki.dovecot.org/Plugins/Zlib ] and also read [ extremeshok.com/6092/postfix-enable-compression-zlib-plugin/ ]. But it's not clear to me what the best method is to enable this and to compress existent e-mails. Hopefully someone uses this and is willing to share Thanks!