@using BlogEngine.NET.Custom.Widgets
@{
    var showThanks = false;
    var showForm = false;
    var showMsg = false;
    var email = Request.Form["txtNewsletterEmail"];

    if (IsPost)
    {
        try
        {
            var addr = new System.Net.Mail.MailAddress(email);
            Newsletter.AddEmail(email);
            showThanks = true;
        }
        catch
        {
            showForm = true;
            showMsg = true;
        }
    }
    else
    {
        showForm = true;
    }
}
<div class="Widget widget newsletter">
    <h4 class="WidgetHeader widget-header">@Model.Title</h4>
    <div class="WidgetContent widget-content" style="padding: 20px">
        @if (showThanks)
        {
        <div style="padding: 20px 40px" id="newsletterthanks">
            <h2 id="newsletteraction">@Resources.labels.thankYou</h2>
        </div>
        }
        @if (showForm)
        {
        <div id="newsletterform">
            <p>@Resources.labels.notifiedPublished</p>
            <label style="font-weight:bold" for="txtNewsletterEmail">@Resources.labels.enterEmail</label>
            <input type="text" style="width:98%;" class="form-control" id="txtNewsletterEmail" name="txtNewsletterEmail" />
            @if (showMsg)
            {
                <span>@Resources.labels.enterEmailAddress</span>
            }
            <div style="text-align:center; margin-top: 10px">
                <input type="submit" class="btn btn-primary" id="btnSave" name="btnSave" value="@Resources.labels.notifyMe" />
            </div>
        </div>
        }
    </div>
</div>