Facebook is going to mail out postcards to people who wish to purchase US election-related ads on its social network in order to verify their identities and confirm their locations.

The postcard, which will contain a special verification code, will only apply to those who want to purchase advertising that mentions a specific candidate – not issue-based ads – Reuters reports.

The news of postcard verification comes after Facebook announced in October last year that it was going to start requiring political advertisers to confirm their identities, following the Russian influence debacle. At the time, Facebook only said that it would require advertisers to verify “both their entity and location” but did not specify how they would do this. Now, this has become a little clearer.

The verification process was announced at the same time as the social network said it would begin testing a ‘View Ads’ feature in Canada, which enables Facebook users to see the ads a Page is running on Facebook, Instagram, and Messenger. This feature will begin rolling out to the US and the rest of the world by summer of this year.