I realise I'm probably a bit behind the times here, but I've been using smtp.xtra.co.nz quite happily for some time now, although I did hear rumours of it being turned off in the near future. My connection is with Xtra, but my e-mail address is with another provider, and no, I can't send through them. Tried to send an e-mail from my T-Stick today but it was rejected, same thing on my home Xtra DSL connection. Changed to send.xtra.co.nz, added in authentication settings, and everything works as it's meant to.
So what I guess I'm asking is, if you're not using send.xtra.co.nz, outgoing won't work anymore, right?