controllers>messages_controller.rb

class MessagesController < ApplicationController
  def new
    @message = Message.new
  end

  def create
    @message = Message.new(message_params)

    respond_to do |format|
      if @message.valid?
        MessageMailer.contact(@message).deliver_now
        format.html { redirect_to new_message_url, notice: 'We have received your message and will be in touch soon!' }
      else
        format.html { render :new, notice: 'Ops.. there was an error sending your message. Please try again.' }
      end
    end
  end

  private

  def message_params
    params.require(:message).permit(:name, :email, :phone_number, :body)
  end
end

mailers>message_mailer.rb

class MessageMailer < ApplicationMailer
  require 'sendgrid-ruby'
  include SendGrid

  def contact(message)
    @message = message

    from = Email.new(email: '[email protected]')
    to = Email.new(email: @message.email)
    subject = 'casineros cubanos Blog'
    content = Content.new(type: 'text/plain', value: "Hi dear #{@message.name}! Thanks for your massage, we will get back to you soon.")
    mail = SendGrid::Mail.new(from, subject, to, content)

    sg = SendGrid::API.new(api_key: ENV['SENDGRID_API_KEY'])
    begin # to read error messages
        response = sg.client.mail._("send").post(request_body: mail.to_json)
    rescue Exception => e
        puts e.message
    end

    puts response.status_code
    puts response.body
    puts response.headers

  end
end