Conditional format duplicates for part of cells only

[angeloudaki]

Anyone know the conditional formatting formula for highlighting cells where characters before '@' match? These characters before '@' can range from 3 to 6 letters/numbers in length so I can't use the "first 4" formula, and the characters after the '@' also differ so I can't use that as an identifier... AAAGH!

 

[Peter_SSs]

Is this what you mean?

Excel Workbook
	A
1	abc@def
2	tom.smith@somewhere.com.uk
3	abc@anywhere.com
4	abcd@def
5	Jim@jam
6	tom.smith@somewhere.com.uk
7
8
9
10
CF Dupes

Cells with Conditional Formatting
Cell	Condition		Cell Format	Stop If True
A1	1. / Formula is =COUNTIF(A$1:A$10,LEFT(A1,FIND("@",A1))&"*")>1	Abc