Use AWS SESv2 SDK as an ActionMailer delivery method (API call instead of SMTP)

aws_ses_delivery_method.rb

# Why?
# * May use same IAM role or account in use for other app features.
# * Avoid sharing same SMTP credentials across multiple apps.
#
# Alternatives:
# * https://github.com/aws/aws-sdk-rails (may be overkill)
#
# Gemfile:
#     gem 'aws-sdk-sesv2'
#
# config/initializers/aws_ses_delivery_method.rb:

class SESV2DeliveryMethod
  def initialize(client_params)
    @client = Aws::SESV2::Client.new(client_params)
  end

  # @param [Mail::Message] mail
  def deliver!(mail)
    @client.send_email(
      {
        from_email_address: Array(mail.from).first,
        destination: {
          to_addresses: mail.destinations,
        },
        content: {
          raw: {
            data: mail.encoded,
          },
        }
      }
    )
  end

  def settings
    {}
  end
end

# Alter to handle credentials how you prefer:
ActionMailer::Base.add_delivery_method :ses, SESV2DeliveryMethod,
  region: ENV['AWS_REGION'] || Rails.application.credentials.dig(Rails.env.to_sym, :aws, :region),
  credentials: Aws::Credentials.new(
    ENV['AWS_ACCESS_KEY_ID'] || Rails.application.credentials.dig(Rails.env.to_sym, :aws, :access_key_id),
    ENV['AWS_SECRET_ACCESS_KEY'] || Rails.application.credentials.dig(Rails.env.to_sym, :aws, :secret_access_key)
  )