UPDATE: As of around 10:30 on 11 October, Critical Path are now exclusively dealing with BTi incoming mail. Yahoo! are no longer in the loop at all.

According to an interview given to The Telegraph, BTinternet's email services are being moved to BT-Mail following hacking claims.

UPDATE 10th July: Yet more accounts have been hacked in the last 24-hours, so the problem continues.

We've seen a huge increase in spam coming from yahoo.com e-mail servers.

Many accounts have been compromised, more come in every day. There is much talk on the web about this and as of this morning the problem ain't fixed!

Currently the spams are punting links to fake pages promoting work at home or diet scams.

Both BTinternet (but only for the time being) & now Sky e-mail services in the UK are outsourced to Yahoo! so those accounts are also vulnerable to hijacking.

Our advice once hacked:
You MUST change your password immediately! If the same password has been used elsewhere then you change it there too as those are also now at risk. If you need a password suggestion: Think of a line from your favorite song (or poem if you like) and use the initial letters from each word, including capital letters and punctuation. Your new password must be at least ten apparently random letters for it to be secure.

Following a single complaint from our incoming server MX5 (which forwards no other mail into AOL); AOL in their wisdom have blocked the server:

554 CON:B1 The IP address has been blocked due to a spike in unfavorable e-mail statistics.

We are tmpfailing AOL's servers on MX5 so messages will be delivered to the alternative server and so we can still continue to report abuse to AOL. Here is the message in full (with some redaction) which we wish to report as spam:

From around 13:36GMT GlobalNet's (AKAMadasafish) servers have been rejecting forwarded mail:

2010-12-23 15:34:12 1PVlid-0001P6-CG ** REDACTED@@globalnet.co.uk <REDACTED@@example.com> R=nsNaR T=ST: SMTP error from remote mail server after initial connection: host mx-ironport.core.plus.net [84.92.1.97]: 554-mx.ptn-ipin02.plus.net 554 Your access to this mail system has been rejected due to the sending MTA's poor reputation. If you believe that this failure is in error, please contact the intended recipient via alternate means.

Unsure why at present, the server is not on any blocklists. The eggheads at Ironport have decided, for reasons only known to them, that one of our servers has a "Poor" reputation. This is based on around two weeks of mail (just a few dozen), none of which were SPAM, as our client confirms. We've been in business for over 13 years BTW.

Solution - we are no longer forwarding mail into PlusNet. Instead we've just finished setting up our affected clients with their very own POP3 mailboxes.