On 16/05/2016 10:14, Broadback wrote:
This morning when attempting to send messages from any email (I have a
number) to any address I get this error:

An error occurred while sending mail: The mail server sent an incorrect
greeting: Your IP address is on the XBL blacklist! Sending denied.
For further information and delisting procedure,
please see http://www.spamhaus.org/query/bl?ip=80.229.179.189.

The messages into the sent box, but is not received.
Any ideas please? I am running under windows 10, both have been stable
for some time.

As others have indicated, first check you don't have a trojan running on
any device on your network.

If Plusnet are like any othe ISP with dynamic IP address, I suggest you
switch off your router for 10 minutes or so, and after switching on hope
you might be allocated a new "clean" IP address.