Kalob integrates (web)mail, calendar, todo, filesharing...

In basis it is a combination of well known and solid opensource software, including Postfix, MySQL and Roundcube webmail for example.

Nothing to add, great documentation at https://docs.kolab.org/installation-guide/ubuntu.html ... for a single all-in-one server setup

Scale down (for small environments)

Not really needed, but the number of daemons can be drastically reduced.

Change /etc/cyrus.conf in order to support "modern" imap with STARTTLS only.

• disable pop3, pop3s, imaps

Restart cyrus with service cyrus-imapd restart

Trim down the number of apache daemons in /etc/apache2/mods-enabled/mpm_prefork.conf.

• StartServers 1
• MinSpareServers 2
• MaxSpareServers 3

Restart apache with service apache2 restart

walleced?

Scale out to the enterprise!

For SOHO a single server will be sufficient in most cases, but for larger organization you want to have a fully scalable setup. Kolab consists out of about 10 daemons that can all

https://docs.kolab.org/deployment-guide/multi-server.html#deployment-multi-server-for-each-service