"No Need To Reply". Used mainly at the end of a text message when you send a text message to someone and they would normally text back with "OK" or "k" or "allright". Used so that when they normally would respond with "ok", it will save you the trouble of getting another text message or looking at your phone that will say "ok"
Something to add to the end of an email if there is no need for a further response. It doesn’t mean “don’t respond.” It means “you can respond but you don’t have to.”