> Do we really need to send plain versions or it's just a second system syndrome of doing everything "right"?
Yes, you do need to send plain versions. I make my e-mail clients to use plain
text version first, and if that's not available, HTML version dumbed down to
plain text. The cases when somebody needs to send formatted e-mail are really,
really rare. Though...
> From day to day, we send lots of emails and a huge fraction of those are of marketing nature.
...I delete marketing e-mails on the spot.