OK I have a need to send emails from the card to the members but the email content has to change from time to time (surprise)
The way I solved it is by adding a custom filed (Text). So before I send the email I will type the message I want and in butler I add the content to the static content (I than clear the filed content so the field is ready to be reused. At the moment there is no easy workaround to the need to send the email to all members.
Its seems that it should be very easy for Trello to add a card feature that will do exactly that and will also allow to select the members your wish to send the email to.
Just a thought