Related Clues:

• Proof of mailing
• Visa marking
• Sender's need
• Album feature
• Re-inkable item
• Thirty-nine-center
• Make impressions
• Stamp canceling a stamp
• Philately specimen
• OK, in a way
• Visa feature
• Penny Black was the first one
• Post office purchase
• Some vegans won't lick it
• Abolish (with ''out'')