DAVx⁵ has been successfully tested with Mailfence.

Mailfence is a secure and private mail service, that provides an end-to-end encrypted email with digital signing.

DAVx⁵ settings

Base URL:

Contact group method: groups are per-contact categories (contact groups are mapped to Mailfence contact tags)

User name and password: your Mailfence login data

WebDAV setup

You can mount folders from Mailfence Documents (virtual drive) using the DAVx⁵ WebDAV mounts feature.

WebDAV URL:<user name, all lower-case>

User name and password: same as for CalDAV/CardDAV

Some operations like video streaming won't work because the server doesn't support range requests.