My client has been using smtp.xtra.co.nz in his Outlook setup and had sending probs to only one particular email address (550 invalid recipient). Sending from webmail worked fine.
After changing setup today to send.xtra.co.nz it is all ok.
So is smtp.xtra.co.nz officially obsolete even though it sort of works? They have been talking about obsoleting it for years.
But there are a lot of installs out there eg scanners (some which can't do SSL and authentication) using smtp.xtra.co.nz