[excel] If two cells match, return value from third

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
Column C: List of 100 specific order numbers that I need the email address for

So, I'm looking to search column A for a value that matches C, and return the email address from column B in a new column (D).

The current formula almost works, but instead of returning the email address where A matched C, it returns the email address from the same row.

=IF(ISERROR(MATCH(C2,A:A,0)),B2)    

Essentially I just need B2 in the formula above to return the value from the same line that matched.

All you have to do is write an IF condition in the column d like this:

=IF(A1=C1;B1;" ")

After that just apply this formula to all rows above that one.

=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