If two cells match, return value from third

Question

Here\'s a simple explanation of what I\'m having trouble with.

Column A: List of 2300 order numbers
Column B: Email Address associated with an order number
C

Answer 1

=IF(ISNA(INDEX(B:B,MATCH(C2,A:A,0))),"",INDEX(B:B,MATCH(C2,A:A,0)))

Will return the answer you want and also remove the #N/A result that would appear if you couldn't find a result due to it not appearing in your lookup list.

Ross