From Longman Dictionary of Contemporary Englishpostmarkpost‧mark /ˈpəʊstmɑːk $ ˈpoʊstmɑːrk/ noun [countable] TCMan official mark made on a letter, package etc to show when and where it was posted —postmark verb [transitive] The letter was postmarked Iowa.
Examples from the Corpus
postmark• But they could not find such a postmark.• I wanted to shriek, every time I went to the mailbox and there was a Charlottesville postmark.• It uses digital signatures and requires recipients to download free software to read the electronic postmark.• And the barely legible postmark removed the last shred of doubt about who had sent it.• The central London postmark didn't give any clues, nor did the good quality envelope.• Reluctantly, first examining the postmarks at length for clues, I open them.• He hoped that the postmark might testify to his mobility and grit.• It came in a plain white envelope with a New York postmark and had no return address.From Longman Business Dictionarypostmarkpost‧mark /ˈpəʊstmɑːkˈpoʊstmɑːrk/ noun [countable] an official mark made on a letter, showing when and where it was sentThe letter had a London postmark. —postmarked adjectiveApplications must be postmarked by midnight the day before the auction. 