To ensure that your Prosody instance will federate properly with the rest of the XMPP network, particularly with Google's "GTalk" service (i.e. the "@gmail.com" chat tool,) we must set the SRV records for the domain to point to the server where the Prosody instance is running. We need three records, which can be created in the DNS Management tool of your choice:

Service: _xmpp-server Protocol: TCP Port: 5269
Service: _xmpp-client Protocol: TCP Port: 5222
Service: _jabber Protocol: TCP Port: 5269

The "target" of the SRV record should point to the publicly routable hostname for that machine (e.g. "squire.bucknell.net"). The priority and weight should both be set to 0.