Hotmail fixed the problem today at 12:30 p.m., said Laura Norman, product manager for MSN Hotmail. The problem had been caused early yesterday evening during a "routine site adjustment" she said.
"The multimail issue has been solved," she noted. "There was an issue where multiple mail was sent. It's unclear how many members were affected and how many pieces of mail were sent out."
Not every piece of mail went out multiple times. But many pieces were copied several times and there was a multiplier effect when the pieces were then shipped through email lists.
While some Internet service providers noticed no problems, others had to block Hotmail altogether to keep their servers from being deluged.
Hotmail on Monday announced it had 30 million accounts, cementing its position as the top free email service. But size does come at a price. When a service as large as Hotmail or America Online suffers a glitch, problems are magnified by their size.
One administrator during the outage suggested that Hotmail stop all its email to save the Net from the onslaught.
"When they have a problem, it's a big problem for everybody else," said Jeff Wasilko, email administrator for a cable modem ISP. His service, in fact, was blocking Hotmail. "If they realize there's a problem they should pull the switch, rather than mail bombing the rest of the Internet, until they can get it under control."
Some of his customers reported getting 15 to 20 copies of each message from Hotmail. "It's a pretty big impact because everyone who has email is getting hit pretty hard," he said.