<System.Web.Services.WebMethod()> _
    Public Shared Function IsEmailAvailable(ByVal email As String) As Boolean
        Dim emailAddress As String = Membership.GetUserNameByEmail(email)
        Return (emailAddress Is Nothing)
    End Function


    If IsEmailAvailable(True) = True Then
        modalPopupEmail.Show()
        e.Cancel = True
    Else

    End If