Windows live mail

I thought I had eliminated this live email account account. What happens now
is when someone sends an email to my bigpond mail (nailuj6@xxxxxxxxxxx) they
get this error message. The mail arrives at its intended address but they get
this message in return. Bit confusing. Anybody know how I stop this from
happening. I'm only learning so any help would be appreciated.

This Message was undeliverable due to the following reason:

Each of the following recipients was rejected by a remote mail server.
The reasons given by the server are included to help you determine why
each recipient was rejected.

Recipient: <nailuj6@xxxxxxxxxxx>
Reason: Requested action not taken: mailbox unavailable

Please reply to <Postmaster@xxxxxxxxxxxxxx>
if you feel this message to be in error.