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.
Our response is to block hacked accounts for a period. We will immediately remove the restriction once we hear from the account holder who should contact us using this form.
On the 1st April, Yahoo! added a page to their help site to aid affected users.
FOOTNOTE: The spammers are now also using a botnet to distribute their message, so it's probably becoming more difficult to access these accounts.