Cant send emails with 550 REJ-CON-002 as BT host at
Is reported by cbl.abuseat.org as being infected thus mail transfer is blocked.
This IP is infected with, or is NATting for a machine infected with Win32/Zbot (Microsoft).
Are you trying to send email directly from your network/PCs?
It's much better to use BT's smarthost for sending mail (aka SMTP)- you can use it even if you don't have a btyahoo email address. Full details of setup are here:
You will find that a lot of Dynamic IP addresses are blacklisted (or getting that way). Resetting your HomeHub might fix it (it might get a new address that is not blacklisted), but I can't guarantee it.
Hope this helps,