In a written statement, VM said that it had been suffering sporadic problems for some customers with @blueyonder.co.uk email addresses and had been working with its platform supplier, Microsoft, to ascertain the source of the problem. The company also took this occasion to issue a statement of apology to its customers.

According to reports by The Register, the outages provoked VM to call in Microsoft engineers to assist with an pressing Exchange upgrade on its servers. A VM spokesman says this malfunction has helped to speed up a previously-discussed program to migrate the email servers to a Microsoft Exchange 2003 platform. The upgrade is expected to take in the region of two weeks, as long as the company faces no further issues.

VM says that a disconnected hardware problem on an authentication server was also the foundation of a slowdown across all eight clusters, but this has reportedly now been resolved.