Release series 3.4 appears to have introduced a bug resulting in the inability to communicate with servers serving a subdomain of the xmpp.domain.
For instance, email@example.com cannot communicate with firstname.lastname@example.org. This is due to the fact that Openfire assumes that a JID containing the xmpp.domain is a locally hosted component if the JID’s domain is not equal to the xmpp.domain. This bug was discovered in Openfire 3.4.4 and still exists in the recently released Openfire 3.5.0. I’ve attached a patch.