Steve Rowbotham had been suspended after the company investigated evidence that he was not delivering direct mail.
Royal Mail revealed Rowbotham, who worked in Burton Joyce in Nottinghamshire, had been dismissed in a statement on Friday. He has the right to appeal.
Last year it suspended a postman, Roger Annies, for distributing leaflets on his round advising people how to opt out of receiving unaddressed mail. Annies was later moved to a role in a sorting office.
Separately, Royal Mail chief executive Adam Crozier has written to the Communication Workers Union to offer talks at the conciliation service Acas but is not prepared to raise its 2.5% pay offer.
The CWU is meeting on Thursday to set dates for the strikes members voted in favour of last week.