Install this project:
serverless install --url https://github.com/sanddevil/serverless-php-contact-form.git
composer install -o --no-dev
serverless deploy
You will need to add your own email addresses to this file. You will easily see the placeholders.
This is blogged at http://badzilla.co.uk/drupal-8-static-site-aws-api-gateway-lambda-and-ses-form-processing
The blog is a sequence of blogs on turning a Drupal 8 site to a static site http://badzilla.co.uk/Drupal8-Static
There are a sequence of blogs on using PHP and Serverless together at http://badzilla.co.uk/real-world-php-lambda-app
Big thanks to Andy Raines. For documentation on his serverless-php repo upon which this repo is based, point a browser to https://github.com/araines/serverless-php