DEAR MISS MANNERS: My email complaint: selective response rates!
If you frequently exchange emails with another person and begin to realize they respond quickly to what is important to them and take forever if it is not -- i.e., it is important only to the sender -- it is offensive and inconsiderate.
GENTLE READER: It seems to Miss Manners that we already had an instrument that interrupted others and demanded that they give us their attention this instant.
That was what the telephone did before we realized how annoying it was and built in some protection, or even stopped using it. Please do not attempt to impose this demand on a convenient way of getting to people quickly without compromising their ability to sort their messages for degrees of urgency.