On Ubuntu 16.04... It worked with Winterfell, but when I changed to Kolab 16 the /etc/php/7.0/mods-available/kolab.ini changed from:
; Kolab libraries extension=dummy.so extension=kolabformat.so extension=kolabobject.so extension=kolabshared.so extension=kolabcalendaring.so extension=kolabicalendar.so
to
; Kolab libraries extension=kolabobject.so extension=kolabshared.so extension=kolabcalendaring.so extension=kolabicalendar.so
and when using Roundcube I get: PHP Fatal error: Uncaught Error: Call to undefined function dl() in /usr/share/php/kolabformat.php:22.
Setting enable_dl=On in php.ini does not help. Only adding extension=kolabformat.so to kolab.ini works. I'm not sure we still need dummy.so on PHP7. Something to verify.