Answer: stamp

AnswerCrossword Clue
STAMPSnail mail must
STAMPImprint
STAMPSnail-mail need
STAMP"Forever" post office product
STAMPShow petulance
STAMPLetter attachment?
STAMPMake an impression, maybe
STAMPExtinguish, with "out"
STAMPIt may be stuck in the corner
STAMPIt's canceled when it's accepted
STAMPPhilatelist's purchase
STAMPPhilatelist's find
STAMPOfficial imprint
STAMPSnail mail attachment
STAMP34-cent purchase
STAMPAn e-mail doesn't need one
STAMPSnail-mail attachment
STAMPMailing need
STAMPImpress
STAMPFollower of rubber or date
stampto bring the foot down heavily
STAMPFood or rubber follower
STAMPEnvelope addition
STAMPImpression
STAMPMake an impression?
STAMPNotary Public's need
STAMPVisa clearance
STAMPPost office purchase
STAMPPut one's foot down
STAMPIt takes a licking
STAMPPostage
STAMPEnvelope attachment
STAMPPhilatelist's buy
STAMPAbolish, with "out"
STAMPPart of a collection
STAMPNotary's need
STAMPWord after date or time
STAMPE-mail's lack
STAMPSnail mail need
STAMPIt may be licked