Twitter's support account today announced that Twitter used some customer email addresses and phone numbers that were provided for account security for advertising purposes, which Twitter says was done "unintentionally."
More specifically, email addresses and phone numbers were used in Twitter's Tailored Audiences and Partner Audiences advertising systems. Tailored Audiences is a feature that's designed to let advertisers target ads to customers based on the advertiser's marketing lists, while Partner Audiences is similar.
According to Twitter, when an advertiser uploaded a marketing list, it "may have matched" people on Twitter to their list based on the email or phone number the Twitter account holder provided for security purposes.
We recently found that some email addresses and phone numbers provided for account security may have been used unintentionally for advertising purposes. This is no longer happening and we wanted to give you more clarity around the situation: https://t.co/bBLQHwDHeQ — Twitter Support (@TwitterSupport) October 8, 2019
Twitter says that it "cannot say with certainty" how many people were affected, and the company has issued an apology. "We're very sorry this happened and are taking steps to make sure we don't make a mistake like this again," reads a help document.
Personal data was not provided externally with partners or other third parties, and as of September 17, the issue has been fixed and phone numbers and email addresses collected for account security are no longer being used for advertising.
