My first attempt at a solution, were I to actually try something like this - say, with my hypothetical chrome/firefox extension called LikeMail - would be to se

My first attempt at a solution, were I to actually try something like this - say, with my hypothetical chrome/firefox extension called LikeMail - would be to send out a canned email with custom headers.: "enobrev has read and 'liked' your message with the LikeMail chrome extension! Download it _here_ so you can do the same with your emails." Then on the recipient's client, if they have LikeMail, consume that message and hide it, while showing the appropriate signaling in the inbox, etc. Definitely a clunky workaround, and can easily be considered spammy, I suppose, although if that automated message were customizable, maybe less so. I think the reason for the email (as opposed to skipping it) is to convey the info the action of "liking" is meant to convey. Essentially if I hit "like" button in LikeMail I'm trying to tell the sender "I read and liked your email". Sending nothing would go against that intention.