Charles, all you need to do is the following (effect described is when using the Fastmail web interface on a PC):
In
Settings>Mail>Preferences>Writing, make these choices:
- Message format: Rich text
- When replying, use the same format as the original message: Disable (do not check)
That combination has this effect:
- New messages you compose will be by default created in HTML format.
- Replies to messages will ignore the format of the original message and will always be created in HTML format.
- You can change the message format to plain text on the fly using the More button in the upper right.
Bill