To install SyncEvolution on a apt-based Linux distribution like Debian or Ubuntu add the repository to /etc/apt/sources.list with: deb http://www.estamos.de/download/apt stable main The repositories are signed. To import the key, use: apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 43D03AD9 This should import the following master key and several sub-keys: apt-key finger ... pub 4096R/43D03AD9 2015-11-18 Key fingerprint = BF01 9331 6B3A 3673 F3DA 5544 A36D BD13 43D0 3AD9 uid SyncEvolution sub 4096R/E598098C 2015-11-18 sub 4096R/87705E44 2015-11-18 [expires: 2016-11-17] ... Once the sub-key expired, you will get warnings from apt. Then repeat the "apt-key adv" command above to get the current one. Finally install the syncevolution package: aptitude install syncevolution-bundle # Just the files, no dependencies. Only the # parts that have the necessary system components # installed actually work. aptitude install syncevolution-evolution # Pulls in all Evolution dependencies from the distro. aptitude install syncevolution-kde # Pulls in all KDE dependencies from the distro. aptitude install syncevolution-activesync # Pulls in additional packages for ActiveSync from syncevolution.org. See http://www.estamos.de/projects/SyncML/Installation.html for details.