yes, i think this is must-have featured. MailChimp have this featured.
try this page, it's by mailchimp
+1 on this
+1 This would be a nice feature
+1 It would be nice to have this done automatically... it is possible to use the Mailchimp version, but that won't convert the <webversion> and <unsubscribe> links properly, which leads to extra fiddling.
+1 I agree. A must-have feature. It is just annoying to have to do it manually when it should be pretty easy to implement it.
The plain-text box to cut and paste into does work, but it sure would be nice to have an auto-generated version that pre-populates that box we could scroll through to ensure it transferred correctly. Including plain-text version of the email was one whole point (1.0) better in SpamAssassian - so likely this would help ensure emails are delivered better as well.
+1 would be good!