On system were the default shell is not bash, the autoresponder script can fail on existing installations, as the existing /etc/kopano/autorespond config file still contains a bashism, while the autoresponder has been switched to use /bin/sh.
This will not occur no fresh installations where the new config is already correct.
Error in /var/log/kopano/server.log as follows.
Existing config file
Fixed config file
Please see https://jira.kopano.io/browse/KC-967 for more information.