Email template formatting removed after upgrading to Rails 6.1

We recently upgraded our monolith from Rails to, but after doing that, some of our formatting in our HTML email templates gets removed upon sending the email (we use haml). Has anyone experienced this before?

The gems we use are:

  • gem ‘inky-rb’, ‘’
  • gem ‘liquid’, ‘4.0.0’
  • gem ‘mailgun-ruby’, ‘1.1.9’
  • gem ‘roadie-rails’, ‘2.2.0’
  • gem ‘valid_email’, ‘0.1.0’

It doesn’t seem like ActionMailer has changed much, and our versions of mail and haml aren’t too far behind. Thank you!