postage meter

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A machine used in bulk mailing to print the correct amount of postage for each piece of mail, either directly on the piece or on a label to be put on the piece.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A machine used to print prepaid labels onto pieces of mail, and to record total postage charges.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun meter for bulk mailings that imprints correct prepaid postage on pieces of mail and records the total charge