After readers informed the Register about the problem, the website contacted 1&1 and received an email response apologizing for and explaining the disruption.

According to the statement, the problem arose when 1&1 was updating Microsoft Outlook Web Access software. "Following preparations for an update to new software for Microsoft Exchange 2007 Front-end, one server serving the Outlook front-end has partly been inaccessible as a result of a change in its IP address," the statement read. "The IP address of this server was apparently made available too late for some DNS servers for some ISPs, resulting in some hundred customers using these DNS servers not being able to access their mailbox via Outlook Web Access."

While 1&1 reported that a large majority of DNS servers already incorporated the change, due to different DNS server configurations, some users experienced slow performance. They noted that customers with such an issue should attempt to refresh their DNS cache with the command "IPCONFIG/flushdns." They also suggested that another way to cope with the problem would be to use a different mail-client than OWA until the DNS-server has been fully updated.

According to 1&1, no customers using Linux mail servers or MailExchange customers have been affected.

While this week's update caused some negative attention, early last week, customer feedback and online reputation management services provider RatePoint (ratepoint.com) and 1&1 announced a strategic partnership to integrate RatePoint's platform within all of 1&1's hosting packages.