The initial version of Kopano Core (KC) was forked from the then-current release of (the open-source parts of) Zarafa Collaboration Platform, and superseded ZCP in terms of lineage as ZCP switched to maintenance mode with patches flowing from KC.
The original goal of ZCP was to be a replacement for Microsoft Exchange,[1] so that users could retain Outlook as a client application.
All server-side components (Kopano Core) and WebApp are published under the Affero General Public License (AGPL).
So-called MAPI providers (essentially plugins) abstract and take care of the underlying transport mechanism.
Kopano-server exposes its functionality over stream sockets and uses the HTTP protocol, with data being serialized using SOAP/XML.
Kopano provides several plugins such as Files (cloud and storage access within WebApp), WebMeetings (video conference) and S/MIME (which allows reading and sending encrypted email).
The package in e.g. Debian saw its last update in 2020/Q1, and openSUSE removed it in 2021/Q1 following build failures with contemporary toolchains.