Virgin Media customers have been suffering email outages for several days, prompting the firm to call in Microsoft engineers to help with an urgent upgrade.
A mysterious configuration problem was identified on one of VM's eight email server clusters last Wednesday. Microsft engineers have struggled to identify the cause, forcing several reboots.
The ongoing failure has affected about 10 per cent of VM's ex-Telewest subscribers.
In a statement, the cable firm said:
We have been suffering intermittent problems affecting email access for some customers with @blueyonder.co.uk email addresses. We have been working with our platform supplier Microsoft to establish the cause of this problem and have made good progress, however some issues remain.
We are working to resolve these as a top priority. Virgin Media apologises for any inconvenience this may have caused.
A spokesman said a programme to migrate the email servers to a Microsoft Exchange 2003 platform has been accelerated as a result of the outages.
On the VM support site Alex Brown, a senior product manager, wrote: "It's not been a good week on the email front on the xTW mail platform. On a positive front, yesterday at our senior management change board we made the call to 'go' for migrating the cluster to the Exchange 2003 platform
"This is scheduled to kick off on Monday, and will take about two weeks - as long as we have no further issues."
A separate hardware problem on an authentication server has also caused a slowdown across all eight clusters, reportedly now resolved. ®