The goodbye message is a superb idea, just so everyone knows how professional you were during this period (even though your boss was not). Just send it before

The goodbye message is a superb idea, just so everyone knows how professional you were during this period (even though your boss was not). Just send it before your official termination period (if you specified one) and not after. You should be completely off company resources once you are gone. Include your personal email address in the farewell letter, but do not check company email once you are out the door.