Email needs Headings formatting for accessibility
When writing emails, we are trying to make them as accessible as possible. The MS guidelines (https://support.office.com/en-us/article/make-your-outlook-email-accessible-to-people-with-disabilities-71ce71f4-7b15-4b7a-a2e3-cf91721bbacb?ui=en-US&rs=en-US&ad=US) suggest using headers (h1, h2, h3) in formatting emails. This functionality isn't in mail online, or isn't easily discoverable.
This is stopping my institution from being able to use email online for much of our day to day working.