Fix Markdown/HTML email oddities
Fix Markdown/HTML email oddities

Depends on:
- [ ] https://github.com/alphagov/notifications-utils/pull/59

alphagov/notifications-admin,alphagov/notifications-admin,alphagov/notifications-admin,gov-cjwaszczuk/notifications-admin,gov-cjwaszczuk/notifications-admin,gov-cjwaszczuk/notifications-admin,gov-cjwaszczuk/notifications-admin,alphagov/notifications-admin