Problem
When accessing the webmail part of Open Xchange access is very slow. For example, opening the inbox already takes about 20 seconds.
Environment
You might check the file /var/log/univention/listener.log or other files for entries.
uid=chris,cn=users,dc=multi,dc=ucs "['/opt/open-xchange/sbin/createuser', '--adminuser=oxadmin', '--contextid=10', '--username=chris', '--email=chris user ucs@multi.ucs'
Note the wrong email address which contains invalid spaces. Therefore the listener fails and needs to restart frequently which causes delays.
Solution
Make sure all users are created with correct attributes.