https://www.reuters.com/article/us-usa-election-facebook/facebook-plans-to-use-u-s-mail-to-verify-ids-of-election-ad-buyers-idUSKCN1G10VD

Facebook Inc will start using postcards sent by U.S. mail later this year to verify the identities and location of people who want to purchase U.S. election-related advertising on its site, a senior company executive said on Saturday.