-------------------------------
The code for the contact form
-------------------------------

<div id='contact-box' class="group">
  <div class="span6 clear">
    <form action="/" method="post" class="well">
      <label for="name">Your Name:</label>
      <input type="text" name="name" class="span4" placeholder="John Smith...">
      <label for="email">Your email address:</label>
      <input type="text" name="email" class="span4" placeholder="email@example.com">
      <label for="to">Your message:</label>
      <textarea name="message" cols='30' rows="10"></textarea><br>
      <button type="submit" class="btn" value="Send">Submit</button>
    </form>
  </div>
</div>

------------------------------
In the base application file:
------------------------------

post '/' do 
  configure_pony
  name = params[:name]
  sender_email = params[:email]
  message = params[:message]
  logger.error params.inspect
  begin
    Pony.mail(
      :from => "#{name}<#{sender_email}>",
      :to => 'example@gmail.com',
      :subject =>"#{name} has contacted you",
      :body => "#{message}",
    )
    redirect '/success'
  rescue
    @exception = $!
    erb :boom
  end
end

def configure_pony
  Pony.options = {
    :via => :smtp,
    :via_options => { 
      :address              => 'smtp.sendgrid.net', 
      :port                 => '587',  
      :user_name            => ENV['SENDGRID_USERNAME'], 
      :password             => ENV['SENDGRID_PASSWORD'], 
      :authentication       => :plain, 
      :enable_starttls_auto => true,
      :domain               => 'heroku.com'
    }    
  }
end

-------------
boom.erb is just a template that will show the exception message and the submitted params.