Innovation Technology
=TEXTAFTER(A2, "@")
or,
=MID(A1, FIND("@", A1) + 1, LEN(A1) - FIND("@", A1))
=IF(C2="",CONCATENATE(B2,"@","domain.com"),C2)
=TEXTAFTER( A2 , "@") or, =MID(A1, FIND("@", A1) + 1, LEN(A1) - FIND("@", A1))