Virgin Media customers have been left without email services after a mysterious bug affected one of the company's central email clusters.
The telecoms and broadband firm has said in a statement that it has requested the help of Microsoft to rectify the problem after a number of customer complaints.
One man reported that his emails took 11 hours to arrive, PCPro claims.
A Virgin Media spokesperson has announced that the problem - which has affected around ten per cent of ex-Telewest customers since the beginning of the month - should be rectified soon.
"It's not been a good week and of course we apologise for any inconvenience this has caused," said Alex Brown, senior product manager for Virgin Media.
The problem has affected some of the Virgin Media customers that have blueyonder email addresses. The firm took over Telewest's broadband and TV service last year.
Virgin has recently received criticism for an advertising campaign which competitors felt misled consumers in its representation of the speed of its network.
The "Hate to Wait" campaign has since been cleared of any wrongdoing by industry watchdog Ofcom.