Jira sends HTML emails even when user preference specifies plain text

https://confluence.atlassian.com/jiracoreserver074/managing-your-user-profile-921047238.html#Managingyouruserprofile-Managingemailnotifications says:

In the Preferences section on the Summary page, click the edit icon at the top-right of the section to open the Updated User Preferences dialog box. You can then manage the following:

• Change the Email Type to change the format (plain text or HTML) in which JIRA sends its outgoing email notifications.

I've changed this to plain text in the hope that I'd get reasonably formatted (i.e. readable) emails, but instead I continue to get HTML emails. This wouldn't be an issue if my browser wasn't crap, but I'm more or less forced to use Outlook, and if I want to be able to reply sensibly with it (that is, reply inline with the '>' prefix), I have to make it convert all emails I read to plain text. This results in Jira emails that look like this:

compare this to the much more readable HTML version:

As you can see from the first image, Outlook is still receiving Jira emails as HTML, which is the issue here.