Why wouldn't you just use RegExp? This would have saved you a massive amount of time.
You could have done something like the following

Function validateEmail(email) {
Dim regEx, regVal
Set regEx = New RegExp
regEx.Pattern = "/^([a-zA-Z0-9])+([\.a-zA-Z0-9_-])*@([a-zA-Z0-9_-])+(\.[a-zA-Z0-9_-]+)+/"
regVal = regEx.Test(email)
If RegVal Then
'It is an email address
Else
'It is not an email address
End If
End Function