Feature Request - Retrieve public keys from the DNS, as in RFC-7929

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What's this issue about?

To simplify retrieving the public key of your buddy, the software could look in the DNS of your buddy's email provider (assuming you know their email address and their provider supports RFC-7929).

About the Feature

The IETF recently published RFC-7929 which covers requesting OpenPGP public keys from the DNS records of the recipient's mail provider. There are already several mail providers that support this technology, such as Posteo and Mail.de.