Users fume over Outlook.com email 'carnage'

Microsoft spent last week rejecting emails to Outlook recipients after what appears to be either a fault or overzealous blocking rules, a situation a source described as "carnage."

The problem affects certain IP addresses, whose emails are rejected due to falling foul of reputation rules or appearing on a block list.

A Register reader told us, "At the back end of January we noticed a sudden spike in customers static IPs being rejected by only Microsoft Outlook free / personal accounts."

The message returned was a 550, telling customers to contact their Internet Service Provider (ISP) "since part of their network is on our block list."

A block list is a good thing. It helps stem the flow of spam from networks or addresses associated with junk email. However, the confusing thing for our reader is that his company was not on Microsoft's naughty step for email. A look at ...