"It shouldn't be pretty hard to figure out my e-mail address," Bloomberg said, "and if you send me an e-mail and I don't want to read it, I don't open it. To me it wasn't that big of a deal."
AT&T Inc. said Wednesday that exposed the e-mail addresses - but nothing else - of more than 100,000 iPad users. Only users who signed up for AT&T's "3G" wireless Internet service were affected.
The problem had to do with the way AT&T's website prompted iPad users to log onto their AT&T accounts.
A hacker group that calls itself Goatse Security claims to have found the weakness and said it was able to trick AT&T's site into giving up more than 114,000 e-mail addresses, including those of famous people and government officials.
Bloomberg, who founded the financial information company Bloomberg LP and has an estimated $18 billion fortune, said such glitches are part of modern life.
"We live in a world where information is available all over the place, and there's going to be security breaches every day all over the world," he said. "That's what happens when you have information."
In recent weeks, the mayor has often touted the Apple Inc. tablet as a helpful tool for managing a city of 8.4 million people.
AT&T said Wednesday it would notify all iPad users whose e-mail addresses may have been exposed.
"We take customer privacy very seriously and while we have fixed this problem, we apologize to our customers who were impacted," the company said in a statement.