Special pawn capture move - En-Passant

We receive many emails about invalid pawn moves that are about the En-Passant.  This is a valid but not well know special rule in Chess.

See below an example in the three screenshots.  

1. The position is setup, the white pawn has not made the first move.

2. White pawn moves 2 rows.

3. Black pawn takes the white pawn just as if the white pawn had moved 1 row.

This is a special capture that is only allow after a pawn moves two rows.

Please see this wiki page Wiki page for En_passant for more information.