If you are sending mail from a @xtra.co.nz account you should be using the following: pop3: pop3.xtra.co.nz, SSL,port 995 smtp: send.xtra.co.nz, SSL, with SMTP auth, port 465
If your client doesn't do proper SSL, then use the 110 port without SSL, and 587 without SSL but WITH auth.
You'll find that smtp.xtra.co.nz may work if you are connecting from a telecom provided connection (dial up, fixed line broadband, mobile broadband etc), except you must authenticate if you are connecting from a different network.
If you are using a domain name mail service provided by Xtra/Telecom called officemail. (ie. email@example.com) You'll need to use the following settings: pop3: pop3.officemail.co.nz, SSL,port 995 smtp: smtp.officemail.co.nz, SSL, with SMTP auth, port 465
The same rules apply with non SSL connection.
If you are using a domain name not provided by Xtra/Telecom, you'll need to use your own mail settings. smtp.xtra.co.nz will only work if you are connecting from a telecom connection. In this case, the vodafone smtp server could be an option, or alternatively use your own smtp server (with authetication of course, you don't want open relays on the internet).
Xtra mail server upgraded recently, if you cannot access your email give Telecom a ring to re-authenticate your account at 0800 225 598.