Per PHI1844
https://secure.phabricator.com/source/phabricator/browse/master/externals/amazon-ses/ses.php$460
Needs to be updated to use the V4 Signature model
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To enhance the security of Amazon SES customers, beginning October 1, 2020, support for Signature Version 3 will be turned off (deprecated) in Amazon SES, and only Signature Version 4 will be supported going forward. Amazon SES customers who are currently using Signature Version 3 must migrate to Signature Version 4 by September 30, 2020. After that, Amazon SES will only accept requests that are signed using Signature Version 4. For more information, see the Signature Version 4 signing process in the AWS General Reference [1].
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