THE POSTMAN ALWAYS KNOCKS THRICE?

The story of Please_Mr._Postman? Is quite an odd one. From the wiki above:-

It's famous for being the first Motown song to reach the number-one position on the Billboard Hot 100

The song has been covered several times, including a version by the Beatles in 1963. It became a number-one hit again in early 1975 when The Carpenters' cover of the song reached the top position of the Billboard Hot 100. 

In April 1961, the Marvelettes (then known as the Marvels) arranged an audition for Berry Gordy's Tamla label. Marvels' original lead singer Georgia Dobbins needed an original song for their audition and got a blues song from her friend William Garrett, which she then reworked for the group. Dobbins left the group after the audition and was replaced. 

So, it is now credited as being written by Georgia Dobbins, William Garrett, Freddie Gorman, Brian Holland and Robert Bateman. Some of whom re-worked the song into its final form.

Since the original version hadn't made it into the British charts, few in the UK knew the song "Please Mr. Postman", allowing the Beatles to make it their own among all Liverpool groups.

Beatles author Mark Lewisohn reflects: "Without even realising it (and they'd have been thrilled to know), the Beatles broke the Detroit 'Motown sound' to the British listening public."

Who knew?