I believe that as soon as you sign up for the new MCAT, it shows up on your application and your status will change to hold/processing again. However, shooting an email could not hurt.
HOWEVER...do not take the MCAT unless you know you can improve significantly (5+ points). Rushing to take it again could not only result in another poor score, but also, in you looking as though you have poor decision making skills (e.g. 'jumping the gun', impatient, etc.). In the grand scheme of life, taking another year off will not hurt you, and you can end up saving a lot of money (applying late to MD is lethal unless you have sexy stats).
Best of luck. You will get there!