Email template formatting in drupal 8.1.3

Hello! Thank you for reporting a problem in Drupal 8. As a matter of policy we do not consider support requests at critical priority but please note the following:

Support requests should never be marked "critical" or "major". (It remains possible in the UI though to handle contrib special cases.) If you believe you have run into a bug and it is preventing your site from working at all, post it as a bug report; however, be prepared for others to re-categorize it as appropriate. A higher issue priority is unlikely to give you better support; it is better to describe your issue thoroughly (with clear steps to reproduce it) to help people understand what is wrong.

— https://www.drupal.org/core/issue-priority

It always helps to surround code blocks in the issue summary and in comments with the code tag, for readability. I went ahead and did that for you. One more thing—I noticed you assigned yourself to this issue. Usually, that suggests that you have made yourself responsible for finding the solution.