Facebook’s global director of policy programs tells it will start sending postcards by snail mail to substantiate buyers of ads related to United States elections. Katie Harbath, who described the scheme at a conference held by the National Association of Secretaries of State this weekend, didn’t expose when the program will start, but told Reuters it would be before the congressional midterm elections in November.

The cards will be sent to people who want to purchase ads that mention candidates running for federal offices, but not issue-based political ads, Harbath told, and contain a code that buyers need to enter to verify that they are in the U.S. The program is similar to ones used by Google My Business and Nextdoor when they need to verify business owners or users who want to join closed neighborhood groups, respectively.

Harbath told Reuters that the postcards “won’t solve everything, ” but were the most effective method the company came up with to prevent people from utilizing false identities to purchase ads. In October, Facebook vice president of ads Rob Goldman published a blog post saying that the platform planned to create more transparency around ads by taking steps that include a searchable archive of federal-election ads and requiring political advertisers to substantiate their identity.

Facebook, Twitter and Google executives were called to testify in front of Senate last fall about how Russians employed their platforms to spread misinformation intended to sway the outcome of the 2016 U.S. presidential election campaign. The companies have been criticized for not doing enough to prevent false ad. The questions intensified last week when U.S. special counseling Robert Mueller handed down a situate of indictments charging 13 Russian citizens and three Russian organizations, including a bot farm, with interfering in the presidential election through operations including fake social media accounts.

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