mail_controller.rb

class MailController < ApplicationController
  def send(e)
    begin
      UserMailer.email(required_params[:to],
                       required_params[:from],
                       required_params[:template],
                       required_params[:content])
                .deliver_now
    rescue Exceptions::InvalidTemplateError
      render json: {success: false,
                    reason: 'bad-template'}
    rescue Exceptions::InvalidEmailFormat
      render json: {success: false,
                    reason: 'bad-to-email'}
    rescue Exceptions::InvalidFromEmail
      render json: {success: false,
                    reason: 'bad-from-email'}
    rescue Exceptions::InvalidContent
      render json: {success: false,
                    reason: 'bad-content'}
    end

    render json: {success: true}
  end

  def required_params
    params.require(:to)
          .require(:from)
          .require(:template)
          .require(:content)
  end
end