As you can see in the logs, the DavMail server just ignores the requests for current-user-principal, addressbook-home-set etc.:
D/Wire ( 8836): http-outgoing-5 >> "PROPFIND /users/john.doe@example.com/ HTTP/1.1[\r][\n]"
...
D/Wire ( 8836): http-outgoing-5 >> "<propfind xmlns="DAV:">[\n]"
D/Wire ( 8836): http-outgoing-5 >> " <prop>[\n]"
D/Wire ( 8836): http-outgoing-5 >> " <current-user-principal/>[\n]"
D/Wire ( 8836): http-outgoing-5 >> " </prop>[\n]"
D/Wire ( 8836): http-outgoing-5 >> "</propfind>"
...
D/Wire ( 8836): http-outgoing-5 << "HTTP/1.1 207 Multi-Status[\r][\n]"
D/Wire ( 8836): http-outgoing-5 << "<?xml version="1.0" encoding="UTF-8"?><D:multistatus xmlns:D="DAV:" xmlns:C="urn:ietf:params:xml:ns:caldav" xmlns:E="urn:ietf:params:xml:ns:carddav"><D:response><D:href>/users/john.doe@example.com/</D:href><D:propstat><D:prop></D:prop><D:status>HTTP/1.1 200 OK</D:status></D:propstat></D:response></D:multistatus>"
Pretty-printed response:
<?xml version="1.0" encoding="UTF-8"?>
<D:multistatus xmlns:D="DAV:" xmlns:C="urn:ietf:params:xml:ns:caldav" xmlns:E="urn:ietf:params:xml:ns:carddav">
<D:response>
<D:href>/users/john.doe@example.com/</D:href>
<D:propstat>
<D:prop/>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
</D:multistatus>
So DAVdroid has requested `current-user-principal´, but DavMail does neither report an error, nor does it return the requested property.
