"Our engineers are taking urgent actions to block spammers abusing our email service," said a Tiscali statement on Wednesday. "New hardware is being installed and spam filters are being updated. It is likely to take 7–10 days for these changes to take effect across receiving email providers. During this period, customers will still find some sent emails delayed."
Tiscali has 1.8 million customers in the UK and it has not said how many of them are affected. It did say, though, that not all Tiscali emails are being blocked.
Many anti-spam systems operate by 'blacklisting' mail operators. Domains or mail systems which are delivering massive amounts of spam are identified and all mail from them is blocked by ISPs or mail companies before recipients see the messages.
If a system is hijacked by spammers, as Tiscali's appears to have been, then other systems block Tiscali mail, which affects all senders of email and not just spammers.
On Thursday the company said that it had put in place new email systems and that the sending of emails to non-Tiscali addresses had improved. "We have had reports of intermittent delays with emails sent from Tiscali to other Tiscali email addresses. We are investigating this," said the company.
Meanwhile in the US a man dubbed the 'spam king' has been arrested. Robert Soloway was arrested in Seattle, where prosecutors claim that he is one of the world's most prolific spammers.
Soloway is accused of infecting other computers with a virus which turns them into 'zombies'. Those machines are then used by Soloway's system to send out email on his behalf in massive numbers, according to the allegations.
Soloway has been arrested under identity theft laws and has been charged with mail fraud, money laundering and identity theft.
Prosecutors say that Soloway was responsible for the sending of tens of millions of spam email messages between 2003 and 2007. Soloway could face claims and fines of up to £415,000 if convicted of all the charges against him.