Ability to implement additional mail system

Within AWS, using SMTP to send emails doesn't scale: you need IAM user, credentials, credential rotation, etc.

A good practice to send emails within AWS is to use SES API directly. Permission is handled via IAM roles/permissions, no credentials involved.

Nuxeo Cloud deploy a docker sidecar named aws-smtp-relay that offers a open relay on the host for nuxeo to connect to and forward any email through the SES API.
While this works fine, it has a maintenance cost especially since Remi Cattiau, the original author, left the company.

After looking at Nuxeo MailService and Automation's Mailer, it's clear that sending emails from Nuxeo is only done via SMTP.
In order to "merge" the aws-smtp-relay into Nuxeo Platform, email sending should be revised so that SMTP is an implementation and AWS SES could be an alternative for the platform to use (either implemented via a Marketplace Package or natively in the platform).