0 past simple and past participle of postmark
1 to put a postmark on a letter or parcel:
Almost all of the letters were postmarked in Florida.
Voter registration forms had to be postmarked by midnight.
He talked his way to the front of a line at the post office to have his envelope postmarked before noon.
The forms must be delivered or postmarked by 5.00 p.m. Monday.
