Text Format by Account

The ability to send and receive mail in plain text is nice. It would be better if this could be configured by account. I have one account that I use for listserv type mailing lists and the users there tend to be irritatingly adamant about all mails to the list being in plain text. If I could set that option by account, then it’s not on me to have to remember to set the format every time I create a new message.