Request Return Receipts Sparingly

Many email clients let you request a return receipt. The recipient can respond to that request, and you can be sure they got the message (even before they actually reply). In some cases, this is useful.

In almost all cases, requesting a return receipt is but an annoyance, however. It is annoying to have your email client ask you about return receipts whenever you look at a (non-critical) email, and it is a privacy problem to have your email client send return receipts automatically.

That's why you should use return receipts only sparingly, when they are necessary.