Ah! That explains it, then
As I live over five miles from my nearest phone exchange I was rather short'n'curlied when it came to choosing an ISP to provide DSL to my line - the choice was between BT and PlusNet. Having had such abysmal service from BT when I was on dial-up, I chose PlusNet.
'Nothing could be worse than bloody BT' I thought... how wrong I was.
At the time I signed up with Plus, they asked for an alternative email address (alt to the webmail service they provide as part of the package). Foolishly, I gave them my personal Yahoo webmail address.
I've had various Yahoo accounts for years: those that have been used for mailing lists, usenet groups, bulletin boards and so on have inevitably become spam-clogged eventually. But I've guarded the 'personal' one jealously: it's never been published and my correspondents have respected my requests to keep it out of WAB; out of the CC field, and off the web: consequently, despite having used it daily for six years I've very rarely had more than a couple of iffy mails a week in it.
In the past few days my account has been deluged with spam, mostly for pharmaceuticals and software. I was perplexed until I read The Register's story (and the follow-up on the closure of PlusNet's webmail). Not only has PlusNet let spammers nick my PlusNet email address (which I only use to check their billing notification is correct) but they've given the baddies my long-established Yahoo address for good measure.
About the only thing that PlusNet seems to do reliably is bill for their service - though it wouldn't surprise me if they've managed to give my bloody credit card details to the Russian mafia as well.
The spam cock-up is the last straw. I know most ISPs are as bad as each other and, as I said, my choice here is limited. But I'm fucked if I'm going to pay PlusNet another penny - I'd sooner go through the tedious process of transferring the DSL to someone less incompetent. Bastards!
And, of course, had I not been an avid El Reg reader I'd have no idea who the culprit was because PlusNet has not told its customers anything, leaving them to find out by burrowing deep into its crap web portal.