Starting on Dec. 9 and stretching through to Dec. 13, Yahoo users were unable to access their free email accounts with little explanation from the Internet giant as to why. The high-profile POP-IMAP outage was caused by a "specific hardware outage" in Yahoo's storage system and was determined to be trickier to resolve than initially thought. The problems marked a step back for the company as it works to reinvent itself under CEO Marissa Mayer.
"This has been a very frustrating week for our users and we are very sorry," Mayer said in a statement on Tumblr. "For many of us, Yahoo Mail is a lifeline to our friends, family members and customers. This week, we experienced a major outage that not only interrupted that connection, but caused many of you a massive inconvenience -- that's unacceptable and it's something we're taking very seriously. Unfortunately, the outage was much more complex than it seemed at first, which is why it's taking us several days to resolve the compounding issues."