How to Sign "Mail"
To sign "mail," start by holding your non-dominant hand flat in front of you with the palm facing up, representing an envelope. With your dominant hand, form an "A" handshape (a fist with the thumb resting alongside the index finger). Bring the tip of your dominant thumb to your mouth, as if you are licking a postage stamp. Then, move your dominant hand down and press your thumb firmly against the palm of your non-dominant hand.