Yahoo is scanning people's email for information to sell to advertisers, according to a report in The Wall Street Journal.

The tech giant scans more than 200 million Yahoo Mail inboxes for information about what people have bought, such as receipts from department stores or automotive loan companies, the Journal reported Tuesday. Executives at Yahoo, which was bought by Verizon in June 2017 and placed under its Oath umbrella, have been pitching interest-based advertising to marketers.

Yahoo puts emails into different categories; for example if someone receives a flight confirmation, they might be put into a "frequent traveler" group. That person might then see advertising for hotel chains that might appear on other websites. AOL, also owned by Oath, scans emails in this way as well, the Journal's report said. Data are aggregated and anonymized, so advertisers wouldn't have access to an individual's information.

This type of scanning only applies to emails from organizations and not personal messages, according to Oath's vice president of data, measurements and insights, Doug Sharp, who told the Journal that Yahoo's research shows people prefer personalized advertising. "Email is an expensive system," he added. "I think it's reasonable and ethical to expect the 'value exchange,' if you've got this mail service and there is advertising going on."