"Over the last few days some MSN Hotmail members have experienced slow performance caused by some back-end issues," said a Hotmail spokesperson. "We've been working hard to address these issues, and members will be seeing improved performance soon."
Hotmail declined to specify what kind of back-end issues were causing the delays, which in some cases prevented mail from being delivered. Other users reported being shut out of their accounts.
"I have been unable to access my email for 6 days now," one Hotmail user told News.com. "Finally, 2 days ago instead of just getting a blank page after I log on I got an apology notice saying I caught them in the middle of an upgrade."
Another user trying to log off the service got this message: "Sorry, due to heavy traffic on the network, the page you're trying to reach is temporarily unavailable."
Hotmail said users were experiencing different problems and seeing different explanations depending on what server they accessed.
With more than 30 million users, Hotmail is the largest of the free Web-based email services. Performance problems have dogged the service recently; similar glitches were reported last month, and December brought mail delivery delays and also a glitch that flooded Internet service providers with multiple copies of email.