The error apparently occurred when a U.S.-based MySQL employee mistakenly pasted the e-mail addresses of all the intended recipients into the body of the message.

In a statement confirming the incident, MySQL said it was "working on a stricter process to prevent this from happening again in the future." The company said that it takes the privacy of its database users "very seriously."

The Uppsala, Sweden-based vendor also said that it had sent a follow-up e-mail to all 9,300 affected users, apologizing for the mistake and explaining how it happened.

Robert Brown, an IT project manager and consultant in Hackettstown, N.J., said he received the errant e-mail and was flabbergasted to find so many customer e-mail addresses -- including his own. "I can understand a user error -- you know, 100 or 200 addresses," Brown said. "But more than 9,000? Come on."

Brown said he was so bothered by the incident that he called MySQL to complain.