This one helps u.This
RegularExpressionValidator Helps u in validating emails all required conditions.
<asp:TextBox ID="Email" runat="server"></asp:TextBox>
Validator for checking required field-----
<asp:RequiredFieldValidator ID="EmailRequired" runat=quot;server"ControlToValidate="Email" ErrorMessage="E-mail is required."ToolTip="E-mail is required." ValidationGroup="CreateUserWizard1"ForeColor="#FF3300"></asp:RequiredFieldValidator>
Validator for checking Expression of email address-----
<asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server"ValidationExpression="^[a-zA-Z][a-zA-Z|0-9|]*([_][a-zA-Z|0-9]+)*([.][a-zA-Z|0-9]+([_][a-zA-Z|0-9]+)*)?@[a-zA-Z][a-zA-Z|0-9|]*\.([a-zA-Z][a-zA-Z|0-9]*(\.[a-zA-Z][a-zA-Z|0-9]*)?)$" ControlToValidate="Email" ErrorMessage="Input valid email address!"ForeColor="#FF3300" ></asp:RegularExpressionValidator>