Bloomberg shrugged it off Thursday and said he didn't think it was a big deal.
The billionaire mayor has spent the last several weeks touting his iPad as a helpful tool for managing a city of 8.4 million people.
The former CEO of the financial information company Bloomberg LP said his e-mail address isn't hard to figure out.
AT&T acknowledged the security weakness Wednesday. It said it was notifying all iPad users whose e-mail addresses may have been exposed.
The company said the e-mail addresses were the only information that would have been revealed.