no html/simple plain text selection availbable for single email

[unruhe73]

This is a missing feature request.

Describe the bug
I cannot choose to send and HTML email and keep the standard email type to simple plain text.

To Reproduce
Steps to reproduce the behavior:

1. Select globally text plain for emails
2. Create a new mail

Expected behavior
Possibility to set HTML type for the new single email.

Desktop (please complete the following information):

• OS: Linux and Android
• Desktop Environment, if applicable (on Linux): Xfce for Linux
• Version 4.18 for Linux

Additional context
Add any other context about the problem here.