Twitter sent out emails to thousands of users warning them that their account has been compromised by a third party.

Some of those accounts had indeed been compromised, but other users received the same email after Twitter had accidentally reset too many passwords, even those who were unaffected, said the company. Twitter did not detail the cause or source of the issue, and declined to share details of its size.

"We're committed to keeping Twitter a safe an open community. As part of that commitment, in instances when we believe an account may have been compromised, we reset the password and send an email letting the account owner know this has happened along with information about creating a new password. This is a routine part of our processes to help protect our users," Twitter explained in a statement on Thursday, Nov. 8.

"In this case, we unintentionally reset passwords of a larger number of accounts, beyond those that we believed to have been compromised. We apologize for the inconvenience or confusion this may have caused."

Some of the users who received the email also noticed that some of their tweets had been removed, while other users reported that spam links had been posted from their accounts, without their knowledge. This is a typical characteristic of a compromised account. Meanwhile, other users criticized Twitter's email, arguing that it looked like a "phishing scam," i.e. a message that impersonates an official email in a bid to trick users into providing their personal details.

It remains unclear at this point just what the root cause of the warning emails was, but the statement on the Twitter status page indicates that in this case, the comprehensive scheme of password reset emails was a mistake.

As the Wall Street Journal points out, Twitter was not hacked. The microblogging company simply resets passwords of accounts it believes may have been compromised as a routine, as most large online services do. In this case, Twitter just went to overkill, and targeted too many accounts.

In addition to apologizing for the inconvenience, Twitter also recommended that its users check out the Twitter support page to learn how to keep their accounts secure.