=TEXTAFTER(A2, "@")
or,
=MID(A1, FIND("@", A1) + 1, LEN(A1) - FIND("@", A1))
=TEXTAFTER(A2, "@")
or,
=MID(A1, FIND("@", A1) + 1, LEN(A1) - FIND("@", A1))
Here the example is given for column A:
=COUNTIF($A$2:$A711,$A13)<2
=TEXTAFTER( A2 , "@") or, =MID(A1, FIND("@", A1) + 1, LEN(A1) - FIND("@", A1))