The NTL mail server you were using Graham was blacklisted for spam abuse.
It happened to my dad recently. All of a sudden, his e-mail volume shot down and he got a load of calls saying e-mails were bheing returned for "abuse". He called up thinking the abuse was on his side (I told him someone might of guessed his password and spamming through it), but TS told him that the person sending the e-mail was the abuser. Apparently, there is no way to turn it off, or alter it. They just have to send it from a different server. I thought this was incredible. Noone on BTOpenworld can send him email now it seems.
Here is the part of the e-mail he sent me, with the abuse error report in:
> From: <postmaster@btconnect.com>
> To: <*******@btconnect.com>
> Sent: Friday, May 21, 2004 9:42 PM
> Subject: Delivery Report (failure) for *******@worldnet.att.net
>
>
> > This report relates to your message:
> > Subject: ,
> > Message-ID: <001701c43f75$41755ab0$98967ad5@*******07M07WB>,
> > To: "********" <**********@worldnet.att.net>
> >
> > of Fri, 21 May 2004 20:42:50 +0000
> >
> > Your message was not delivered to:
> > ********@worldnet.att.net
> > for the following reason:
> > Diagnostic was Unable to transfer, -1
> > Information MTA 'worldnet.att.net' gives error message 193.113.154.34
> blocked by blacklist.mail.ops.worldnet.att.net.; Blocked for abuse. Please
> contact the administrator of your ISP or sending mail service.