Don't call us, we'll call you
Don't bother to pursue your application further.
A fuller version of this phrase would be 'Don't call us, we'll call you - if we need to'. Of course, anyone hearing this line can reasonably expect not to need to wait by the phone. It is a quite recent phrase - mid 20th century American, and appears to derive from the brush-off lines given to theatrical auditioners. The earliest citation I've come across is in the Ohio newspaper The Toledo Blade, March 1944, in Dorothy Kilgallen's column The Voice Of Broadway:
"Audition after audition left her with nothing but "Sorry" and "Not the type" and "Don't call us, we'll call you" and a heart that was close to breaking."
It is sufficiently clichéd now to be often shortened to "don't call us" and widespread enough to be used as a term of rejection in a variety of circumstances.