[mikeatlas]

The letter_opener gem is pretty handy to avoid that: https://github.com/ryanb/letter_opener

Or, you could easily just create controller actions which render your emails as well:

@body = mail.body.parts[1].html_part.body.raw_source

render '/mailer_notification/preview.html', :layout => false

And in preview.html.erb: <%= raw(@body) %>