CalDAV Implementation Details

Axigen Documentation

This section describes specifics about Axigen's CalDAV implementation.

Calendar Collections

Axigen allows a CalDAV client to access all the user's calendar folders that exist at the same level as the INBOX.

It should be noted that the calendar collection that is fully supported by Axigen in CalDAV is the user's "Calendar" folder; while other calendar folders (other local folders) can be accessed using CalDAV clients, a number of limitations exist such as:

  • Axigen does not send attendee notifications for any folder that is not the "Calendar" folder

  • Axigen does not implement free-busy queries for any folder that is not the "Calendar" folder

Note: the old Axigen webmail interface allows arbitrary hierarchies, e.g. you can create a structure of calendar folders such as "/Calendar1/Calendar2/Calendar3", all of the folders being calendar folders. 

The CalDAV server that is built in Axigen only allows access to the first level of the hierarchy, so only Calendar1 will be available via CalDAV.

Calendar Collection Paths

For CalDAV clients that do not perform discovery and have to be configured by using a path to a calendar collection Axigen uses the following conventions

  • for local calendar folders

    • local calendar folder called "Calendar" is https://webmail.axigen.url/Calendar/Calendar/

    • local calendar folder called "Birthdays" is accessed via https://webmail.axigen.url/Calendar/Birthdays/

  • for public calendar folders (starting with X2)

    • a public calendar folder called "FooBar" is https://webmail.axigen.url/Calendar/PublicFolders/FooBar/

  • for shared calendar folders (starting with X2)

    • a shared calendar folder shared by "baz" is https://webmail.axigen.url/Calendar/SharedFolders/baz/FooBar/

Collection Paths for Folders that Contain Diacritical Marks

Axigen uses collection paths (HREFs) that contain folder names in IMAP UTF7 modified encoding.

This means that the path for a local calendar folder called "Ciocolată" is: https://webmail.axigen.url/Calendar/Ciocolat&AQM-/. In applications that lack discovery for calendar resources the user will have to input the folder name part of the path in IMAP UTF7 encoding.

Task Collections

Only the local "Tasks" folders is accessible via CalDAV. The path to the Tasks collection is https://webmail.axigen.url/Calendar/Tasks/

Patching Calendar Collection Properties (PROPPATCH)

For local calendars (calendars owned by the CalDAV account), Axigen supports patching a number of properties (such as calendar-color, calendar-order, calendar-timezone).

Using Group Addresses in CalDAV Scheduling

Support for group addresses in CalDAV scheduling is not present in Axigen 10.1.

Group addresses cannot be directly used in scheduling, but a CalDAV server might expand the group address when processing an event originated from a CalDAV client (e.g. by replacing ATTENDEE entries for "" with ATTENDEE entries for group members, say "", "", ""). In Axigen 10.1 group expansion is not implemented.


The CalDAV server runs on top of WebMail so CalDAV logging is controlled by the WebMail logging configuration.

Protocol level CalDAV log sample: