Countif & Subtotal

Hi,
Sorry to ask such a simple question but I am trying to work out email address percentage on a massive workshop 10000+ rows. I have used the following formula but it does not work and i'm confused to why, =SUMPRODUCT(SUBTOTAL(3,OFFSET(A2,ROW(A2:A100)-ROW(A2),0)),(A2:A100="*@*")+0), but it returns 0, if I take the * (wildcard) out it works as long as @ is the only character in the cell, I need it to check to see if the @ is evident as in some cases numbers and other text has been inputted.
Many Thanks
Johnny

Works perfectly, many thanks Tony