this would seem quite obvious, but it is still not working :)...
I have set the general default, the context for the project as well as my own user profile to send Text email. Still it becomes an html email. Even if I switch to Text while composing the e-mail. (Default outgoing mail format for the jira instance is html).
A side effect of this is that the html-code is shown in the Comment created on the JIRA issue when sending the e-mail (since we plain text renderer in the comments).
Example from a Comment:
We're looking for participants for another workshop at Atlassian! We need Jira admins who have interesting custom workflows, issue views, or boards. Think you have a story to sh...
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG
You're one step closer to meeting fellow Atlassian users at your local meet up. Learn more about AUGs