It is very frustrating when a URL sent by WordPress for a change of password will not work if you try to open it by clicking in the BigPond Webmail site
You consistently get the response that the link isn’t valid. I have no idea why this is, but this is my workaround
Instead of trying to open the link through Webmail, I forward the email including the link to my iPhone. When the email appears, open up the message, click the link and VOILA – it works perfectly.
If I ever find out WHY the BigPond webmail always fails, I will update this discussion.