The current message/output/email/templates/email_digest_html.mustache has some problems with RTL languages (and a few technical ones):

• Some attributes like padding-right should be replaced by padding-inline-end
• The text-align and float property uses left/right as values instead of start/end.
• It uses hard-coded "left" and "right" for class names instead of "start" and "end," as in Bootstrap. That does not affect the user experience but should also be changed for consistency.