有些用户一直说系统发送的邮件一直收不到，投诉系统不正常，这时候怎么洗刷冤屈呢？将发送的每一封Email都保存到数据库中，并记录发送的日志，让用户无话可说。

自己创建3个表：

1. MessageFailed - 失败记录（超过5次发送失败就保存到这里）
2. MessageQueue - 信息队列 （成功了就放MessageSucceed，失败5次就保存到MessageFailed）
3. MessageSucceed - 成功记录

使用FluentScheduler，直接在Web端调度，省去Windows服务程序。

FluentScheduler

Automated job scheduler with fluent interface.

相关代码，我是用了IRegisteredObject，避免Application Pool和进程重启造成的Job中断等异常：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace DotNet.Business
{
    using DotNet.Model;
    using DotNet.Business;
    using DotNet.Utilities;

    using FluentScheduler;
    using System.Web.Hosting;

    #region MessageRegistry
    public partial class MessageRegistry : Registry
    {
        public MessageRegistry()
        {
            //不允许重复进入
            NonReentrantAsDefault();

            // Schedule an IJob to run at an interval
            Schedule<MessageJob>().NonReentrant().ToRunNow().AndEvery(1).Seconds();

            //// Schedule an IJob to run once, delayed by a specific time interval
            //Schedule<MessageJob>().ToRunOnceIn(5).Seconds();

            //// Schedule a simple job to run at a specific time
            //Schedule(() => Console.WriteLine("It‘s 9:15 PM now.")).ToRunEvery(1).Days().At(21, 15);

            //// Schedule a more complex action to run immediately and on an monthly interval
            //Schedule<MessageJob>().ToRunNow().AndEvery(1).Months().OnTheFirst(DayOfWeek.Monday).At(3, 0);

            //// Schedule multiple jobs to be run in a single schedule
            //Schedule<MessageJob>().AndThen<MessageJob>().ToRunNow().AndEvery(5).Minutes();
        }
    }
    #endregion

    #region MessageJob
    public partial class MessageJob : BaseManager, IBaseManager, IJob, IRegisteredObject
    {
        private readonly object _lock = new object();

        private bool _shuttingDown;

        public MessageJob()
        {
            //Register this job with the hosting environment.
            //Allows for a more graceful stop of the job, in the case of IIS shutting down.
            HostingEnvironment.RegisterObject(this);
        }

        public void Execute()
        {
            lock (_lock)
            {
                if (_shuttingDown)
                    return;

                //Do work, son!
                new MessageQueueManager(this.UserInfo).Resend();
            }
        }

        public void Stop(bool immediate)
        {
            //Locking here will wait for the lock in Execute to be released until this code can continue.
            lock (_lock)
            {
                _shuttingDown = true;
            }

            HostingEnvironment.UnregisterObject(this);
        }

    }
    #endregion
}

调度的时候，在Global.asax中调度如下：

//FluentScheduler任务调度
FluentScheduler.JobManager.Initialize(new DotNet.Business.MessageRegistry());

Message相关的代码，MessageFailed中的邮件发送Error的记录暂未实现：

#region 重新发送消息
        /// <summary>
        /// 重新发送消息
        /// </summary>
        /// <param name="id">主键</param>
        /// <returns>是否成功</returns>
        public bool Resend(MessageQueueEntity entity, int maxFailCount = 5)
        {
            bool result = false;
            if (entity.MessageType.ToLower().Contains("mail"))
            {
                if (MailUtil.Send(entity.Recipient, entity.Subject, entity.Body))
                {
                    //发送成功，移动数据到MessageSucceed表
                    MessageSucceedEntity entitySuccesed = new MessageSucceedEntity();
                    entitySuccesed.MessageType = entity.MessageType;
                    entitySuccesed.Recipient = entity.Recipient;
                    entitySuccesed.Subject = entity.Subject;
                    entitySuccesed.Body = entity.Body;
                    entitySuccesed.CreateOn = entity.CreateOn;
                    new MessageSucceedManager(this.UserInfo).Add(entitySuccesed);
                    //删除MessageQueue表中的数据
                    //this.Delete(entity.Id);
                    this.DeleteObject(entity.Id);
                    result = true;
                }
                else
                {
                    //更新MessageQueue表中的失败次数
                    entity.FailCount = entity.FailCount + 1;
                    this.UpdateObject(entity);
                    if (entity.FailCount >= maxFailCount)
                    {
                        //发送失败超过5次，移动数据到MessageFailed表
                        MessageFailedEntity entityFailed = new MessageFailedEntity();
                        entityFailed.MessageType = entity.MessageType;
                        entityFailed.Recipient = entity.Recipient;
                        entityFailed.Subject = entity.Subject;
                        entityFailed.Body = entity.Body;
                        entityFailed.FailCount = entity.FailCount;
                        entityFailed.CreateOn = entity.CreateOn;
                        //entityFailed.Error = "";
                        new MessageFailedManager(this.UserInfo).Add(entityFailed);
                        //删除MessageQueue表中的数据
                        //this.Delete(entity.Id);
                        this.DeleteObject(entity.Id);
                        result = false;
                    }
                    result = false;
                }

            }
            return result;
        }
        #endregion

        #region 重新发送所有队列
        /// <summary>
        /// 重新发送所有队列
        /// </summary>
        /// <returns>发送成功数量</returns>
        public int Resend(int maxFailCount = 5)
        {
            int result = 0;
            //每次发一封，避免超时，任务不停启动而listEntity并未重新获取
            List<MessageQueueEntity> listEntity = this.GetList<MessageQueueEntity>(1, MessageQueueEntity.FieldId);
            foreach (var entity in listEntity)
            {
                if (this.Resend(entity, maxFailCount))
                {
                    result++;
                }
            }

            return result;
        }
        #endregion

因为这个后台Job的调度是邮件发送，其实MVC的项目也可以直接用上述代码。