A.2 RFC 3921 (XMPP-IM)

Most of RFC 3921 is supported, with the following exceptions.

Messages of type “headline” are not treated in any special way.

The <thread/> element is not used or generated.

Sending “directed presence” is supported; however, presence stanzas received from contacts not in roster are ignored.

Privacy lists are not supported at all.

jabber.el doesn't support XMPP-E2E or “im:” CPIM URIs.