Add this function in a cell located in a column to the right that is free to pic up the mail adress from the first tab. If you have excel in english swap LETAUPP to VLOOKUP.
This goes for the very first row with data. Then you can just copy the fx downwards by dragging the cell down to the column
=LETAUPP(A2;ParticipantData!A:A;ParticipantData!C:C)