Microsoft has apologised to its UK Hotmail users after some of the software vendor's IP addresses were embarrassingly blocked due to spamming.
"Microsoft is dedicated to providing the most trusted and protected consumer experience on the web," said a Redmond spokesman.
"We worked closely with Trend Micro to fix the issue and the service has now been restored for all customers. We sincerely apologise for any inconvenience and disruption this may have caused our customers."
Universities around the country were hit by the "many messages from Hotmail being rejected" technical cockup, which we reported last Friday.
The problem stemmed from some of Microsoft's Hotmail IP addresses being listed in the MAPS block list, which is maintained by Trend Micro.
Many large institutions such as universities automatically "reject mail outright for any connecting server listed in this block list," said Matthew Newton, who is a systems architect at the University of Leicester.
"It's affecting staff as well as students - I've heard of more complaints from staff (the students are probably all chatting via Facebook!)," he told The Register.
"Personally, I'm surprised that they aren't constantly listed, considering the amount of spam they spew out."
Over the past few weeks we've heard from lots of readers griping about junk email filtering system blunders with Hotmail that have prevented many from receiving email.
On 18 March, Microsoft admitted that Hotmail and Outlook Live users at the University of Bath and the University of Manchester were unable to receive emails for the best part of the day due to a spamming cockup.
Just last week similar problems arose at Bournemouth, De Montfort, Exeter, Portsmouth and Strathclyde universities, all of which were blocking hotmail.co.uk addresses because of a spamming mail server. ®