Although the synchronization with CalDAV is standardized, problems often occur in practice. Editing events on several devices can lead to an information loss. Not all calendar programs are supporting the concept of an all-day event and will create an event that lasts from 12 pm to 11.59 pm.

Furthermore, Webmail does not offer all options for the calendar administration via CalDAV. For instance, it is not possible to create another calendar via a CalDAV program. New calendars can only be created in the web interface and can afterwards be synchronized via CalDAV.

In Thunderbird/Lightning, alerts for events often pop up although they have been confirmed already. This is not a specific problem connected to the synchronization with Webmail but also with different calendar systems in Thunderbird/Lightning. We listed a few possible solutions for this problem in our Thunderbird manual.

You can add several persons to an event and invite them via an automatically created e-mail. Depending on the system, the conformation of participation can be processed incorrectly. When invitees use several e-mail addresses, problems can occur if the confirmation of participation is sent from another e-mail address (for instance, if you sent the invitation to john.doeexample.com and the response is sent from jdoe2example.net).

Moreover, problems can occur if you are invited to an event with several invitees and you delete the event after confirming your participation. As a result, you can be registered as the organizer of the event despite being only a participant.