When iBurst subscribers were unable to send mails to the UK or various European destinations on Monday, they were understandably concerned – especially when technical support people at the ISP explained that its servers had been blacklisted worldwide. 

Although at least one customer reports being unable to send E-mail for almost a day, head of marketing Callia Doucas says that normal service was quickly resumed once the problem had been reported.
As Doucas explains it, one of the ISP's customers attempted to send spam mail, resulting in a blacklisting on spam servers around the world – unfortunately, this meant that part of the iBurst IP address range was blacklisted.
She say iBurst refreshed its IP pool to eliminate the problem, and some other subscribers would have had their mail returned as blacklisted for about an hour.
The service is now running smoothly, says Doucas.