hey HN, I recently published an article going deep into email previewing (in Ruby on Rails, but I think it's relevant beyond Rails).<p>MailCatcher (<a href="https://github.com/sj26/mailcatcher">https://github.com/sj26/mailcatcher</a>) and MailHog (<a href="https://github.com/mailhog/MailHog">https://github.com/mailhog/MailHog</a>) are super handy and easy to run locally. Both spin up an SMTP server which you can direct mail to, and give you a nice web interface to browse mail and preview it.<p>Happy to answer any question! thanks, harrison