| CPC H04L 63/126 (2013.01) [H04L 9/3247 (2013.01); H04L 63/123 (2013.01)] | 20 Claims |
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1. A computer-implemented method when executed by data processing hardware causes the data processing hardware to perform operations comprising:
obtaining, at a first message server, a message for a user of a message service hosted by the first message server, the message from a second message server hosting a second message service, the message comprising a header, the header comprising:
a digital signature signed by an author of the message; and
a list of one or more recipients of the message;
determining that a Domain Name System (DNS) TXT record associated with the message comprises a delegation policy indicating that the header declared all intended recipients of the message;
in response to determining that the DNS TXT record comprises the delegation policy:
determining that the digital signature by the author is valid; and
determining, using the list of one or more recipients, that the user is a declared recipient of the message; and
in response to determining that the digital signature by the author is valid and the user is the declared recipient of the message, indicating the message is authentic.
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