多线程Win窗体应用程序的设计模型和提示

我正在尝试设计一个多线程的windows应用程序，主要为我们的客户快速发送电子邮件给他们的客户(有可能是数百万，因为有一个大的电信公司)，我需要设计提示。(很抱歉Q太长了)

我读了很多关于多线程应用程序的文章。我还阅读了关于SmartThread Pool， . net ThreadPool, Task Parallel Library和其他SO问题。但是我不能带着一个正确的设计来。我的逻辑是这样的:

在程序(电子邮件引擎)开始时，计时器启动并检查数据库(活动表)中是否有状态为1(新活动)的电子邮件活动。

如果有，Campaign subscriber应该从DB中查询，并应该写入另一个名为SubscriberReports表的表(SqlBulkCopy)，并在Campaigns表中将Campaign的Status更新为2。

Timer还监听状态为2的活动，以调用另一个方法为每个订阅用户定制活动，创建具有订阅用户自定义属性的Struct。

第三，调用SendEmail方法通过SMTP发送电子邮件。到目前为止，我所尝试的如下(我知道ThreadPool在这里是错误的，我还有一堆其他错误)。你能建议和帮助我如何设计这样一个应用程序。非常感谢任何帮助。非常感谢你的时间。

private void ProcessTimer(object Source, ElapsedEventArgs e)
{
    Campaigns campaign = new Campaigns();
    IEnumerable<Campaigns> campaignsListStatusOne = // Get Campaign Properties to a List
    IEnumerable<Campaigns> campaignsListStatusTwo = // Get Campaign Properties to a List            
    foreach (Campaigns _campaign in campaignsListStatusOne)
    {
        ThreadPool.QueueUserWorkItem(new WaitCallback(CheckNewCampaign), _campaign.CampaignID);
    }
    foreach (Campaigns _campaign in campaignsListStatusTwo)
    {
        ThreadPool.QueueUserWorkItem(new WaitCallback(CustomizeMail), _campaign.CampaignID);
    }
}
private void CheckNewCampaign(object state)
{
    int campaignID = (int)state;
    DataTable dtCampaignSubscribers = // get subscribers based on Campaign ID
    campaign.UpdateStatus(campaignID, 2);
}
private void CustomizeMail(object state)
{
    int campaignID = (int)state;
    CampaignCustomazition campaignCustomizer;
    IEnumerable<SubscriberReports> reportList = // get subscribers to be sent from Reports table
    foreach (SubscriberReports report in reportList)
    {   // 3 database related methods are here
        campaignCustomizer = new CampaignCustomazition(report.CampaignID, report.SubscriberID);
        campaignCustomizer.CustomizeSource(report.CampaignID, report.SubscriberID, out campaignCustomizer.source, out campaignCustomizer.format);
        campaignCustomizer.CustomizeCampaignDetails(report.CampaignID, report.SubscriberID, out campaignCustomizer.subject, out campaignCustomizer.fromName, out campaignCustomizer.fromEmail, out campaignCustomizer.replyEmail);
        campaignCustomizer.CustomizeSubscriberDetails(report.SubscriberID, out campaignCustomizer.email, out campaignCustomizer.fullName);
        ThreadPool.QueueUserWorkItem(new WaitCallback(SendMail), campaignCustomizer);
    }
} 
private void SendMail(object state)
{
    CampaignCustomazition campaignCustomizer = new CampaignCustomazition();
    campaignCustomizer = (CampaignCustomazition)state;
    //send email based on info at campaignCustomizer via SMTP and update DB record if it is success.
 }