Adding SES sending via SMTP

Add parameters like the following to your YAML config:

    SESSMTP: 'true'
    SESEndpoint: '<the SES SMTP endpoint for your region>'
    SESUsername: '<your SMTP IAM username'
    SESPassword: '<your SMTP IAM password>'

Then your instance will be able to send (not receive) email with a local
MTA via SES.