>Aside: Presence is so chatty, that some mobile clients simply don't handle presence at all. Take WhatsApp for example.

One could also take Hangouts for example. :)

anyways, very informative post and good anecdotes, thank you for sharing.

my understanding of the XMPP spec is that (assuming the server follows the server-client spec, anyways) there's no way to unsubscribe from your contacts' presence notifications and keep them on your roster [and therefore able to be contacted without reauthorization, usually.]

can you confirm/enlighten me? thanks!