blocks|key|688644|text|您是否正在使用.Net+SmtpClient发送电子邮件？It+can+send+asynch+messages+already。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|688645|编辑-如果Emailer+mailer+=+new+Emailer();不是SmtpClient上的包装器，我想这就不会那么有用了。|style|CODE|688646|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/x5x13z6h.aspx^0|T|Z|0|0|5|V|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@$A|Q|B|R|1|S]]|C|$]]|$1|D|3|E|5|6|7|T|8|@$A|U|B|V|F|G]]|9|@]|C|$]]|$1|H|3|-4|5|6|7|W|8|@]|9|@]|C|$]]]|I|$J|$5|K|L|M|C|$N|O]]]]

Are you using the .Net SmtpClient to send email? <a href="http://msdn.microsoft.com/en-us/library/x5x13z6h.aspx" rel="nofollow">It can send asynch messages already</a>.

Edit - If <code>Emailer mailer = new Emailer();</code> is not a wrapper over SmtpClient, this won't be so useful I imagine.

blocks|key|688720|text|如果你正在使用.Net的SmtpClient和MailMessage类，你应该注意一些事情。首先，预计发送时会出现错误，因此捕获并处理它们。其次，在.Net+4中，这些类有一些变化，现在都实现了IDisposable+(MailMessage从3.5开始，SmtpClient在4.0中是新的)。因此，您创建的SmtpClient和MailMessage应该使用块进行包装或显式处理。这是一些人没有意识到的突破性变化。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|688721|有关使用异步发送时的处理的更多信息，请参阅此SO问题：|688722|What+are+best+practices+for+using+SmtpClient,+SendAsync+and+Dispose+under+.NET+4.0|offset|length|688723|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/7276375/what-are-best-practices-for-using-smtpclient-sendasync-and-dispose-under-net-4^0|0|0|0|2A|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Q|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|R|8|@]|9|@$F|S|G|T|1|U]]|A|$]]|$1|H|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|I|$J|$5|K|L|M|A|$N|O]]]]

If you are using .Net's SmtpClient and MailMessage classes, you should take note of a couple things. First, expect errors on the send, so trap and handle them. Second, in .Net 4 there were some changes to these classes, and both now implement IDisposable (MailMessage since 3.5, SmtpClient new in 4.0). Because of this, your creation of the SmtpClient and the MailMessage should be wrapped in using blocks or explicitly disposed. This is a breaking change some people are unaware of.

See this SO question for more info on disposing when using async sends:

<a href="https://stackoverflow.com/questions/7276375/what-are-best-practices-for-using-smtpclient-sendasync-and-dispose-under-net-4">What are best practices for using SmtpClient, SendAsync and Dispose under .NET 4.0</a>

blocks|key|688775|text|线程化在这里不是错误的选择，但是如果你不自己处理异常，它会冒泡并使你的进程崩溃。你在哪个线程上做这件事并不重要。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|688776|因此，不要使用mailer.SendTheMail()，而要使用下面的代码：|688777|new+Thread(()+=>+{+
++try+
++{
++++mailer.SendTheMail();
++}
++catch(Exception+ex)
++{
++++//+Do+something+with+the+exception
++}
});|code-block|syntax|javascript|688778|更好的做法是，尽可能使用SmtpClient的异步功能。不过，您仍然需要处理异常。|688779|我甚至建议你看看.Net+4的新的并行任务库。它具有额外的功能，可以让您处理异常情况，并且可以很好地与ASP.NET的线程池一起工作。|688780|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Threading isn't the wrong option here, but if you don't handle an exception yourself, it will bubble up and crash your process. It doesn't matter which thread you do that on.

So instead of mailer.SendTheMail() try this:

<pre><code>new Thread(() =&gt; { 
 try 
 {
 mailer.SendTheMail();
 }
 catch(Exception ex)
 {
 // Do something with the exception
 }
});
</code></pre>

Better yet, use the asynchronous capabilities of the SmtpClient if you can. You'll still need to handle exceptions though.

I would even suggest you have a look at .Net 4's new Parallet Task library. That has extra functionality which lets you handle exceptional cases and works well with ASP.Net's thread pool.

blocks|key|688850|text|我为我的项目做了同样的事情：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|688851|首先尝试Thread，就像你这样做：|offset|length|style|CODE|688852|我松散的contextException处理problemCommonly说，Thread在IIS+ThreadPool上是个坏主意|688853|因此，我切换并尝试使用asynchronously|688854|“异步”是asp.net+web应用程序中的fake。它只是将队列调用放入队列，并切换上下文|688855|因此，我创建了windows服务，并通过sql表：happy+end来检索值。|688856|为了快速解决这个问题:从mvc端进行异步调用，告诉用户fake是，但在mvc控制器中继续发送作业。|688857|entityMap^0|0|4|6|0|13|6|0|B|E|0|M|4|0|P|9|0|R|4|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|U|8|@$D|V|E|W|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|X|8|@$D|Y|E|Z|F|G]]|9|@]|A|$]]|$1|J|3|K|5|6|7|10|8|@$D|11|E|12|F|G]]|9|@]|A|$]]|$1|L|3|M|5|6|7|13|8|@$D|14|E|15|F|G]]|9|@]|A|$]]|$1|N|3|O|5|6|7|16|8|@$D|17|E|18|F|G]]|9|@]|A|$]]|$1|P|3|Q|5|6|7|19|8|@$D|1A|E|1B|F|G]]|9|@]|A|$]]|$1|R|3|-4|5|6|7|1C|8|@]|9|@]|A|$]]]|S|$]]

I worked same issue for my project:

First tried <code>Thread</code> as you do: 
 - I loose context 
 - Exception handling problem 
 - Commonly said, <code>Thread</code> are bad idea on IIS ThreadPool 

So I switch and try with <code>asynchronously</code>: 
 - 'asynchronously' is <code>fake</code> in a asp.net web application. It just put queue calls and swicth the context 

So I make windows service and retrive the values through sql table: <code>happy end</code>

So for quick solution: from <code>ajax</code> side make async call tell the user <code>fake</code> yes, but continue your sending job in your mvc controller

blocks|key|688945|text|我在这里得到了很多很好的建议...比如确保记得使用IDisposable+(我完全不知道)。我还意识到在另一个线程中手动捕获错误是多么重要，因为没有上下文--我一直在研究一种理论，即我应该让ELMAH处理所有事情。此外，进一步的探索使我意识到我也忘记了在邮件消息上使用IDisposable。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|688946|作为对Richard的回应，尽管我看到线程解决方案可以工作(正如我在第一个示例中建议的那样)，但只要我捕捉到错误...如果不能捕捉到这个错误，IIS就会完全爆炸，这一事实仍然有些可怕。这告诉我，ASP.NET/IIS从来没有让您这样做的意思...这就是为什么我倾向于继续使用.BeginInvoke/委托，因为这不会在出现问题时搞乱IIS，而且在ASP.NET中似乎更受欢迎。|688947|在对ASawyer的回应中，我完全惊讶于客户端中内置了一个.SendAsync。我尝试了一段时间的解决方案，但它似乎没有为我做的把戏。尽管我可以跳过执行SendAsync的代码的客户端，但页面仍然会“等待”，直到SendCompleted事件完成。我的目标是让用户和页面向前移动，同时在后台发送电子邮件。我有一种感觉，我可能还是做错了什么。因此，如果有人遇到这种情况，他们可能想自己尝试一下。|688948|这是我如何100%25异步发送电子邮件的完整解决方案，以及ELMAH.MVC错误日志记录。我决定使用示例2的扩展版本：|688949|public+void+SendThat(MailMessage+message)
{
++++AsyncMethodCaller+caller+=+new+AsyncMethodCaller(SendMailInSeperateThread);
++++AsyncCallback+callbackHandler+=+new+AsyncCallback(AsyncCallback);
++++caller.BeginInvoke(message,+callbackHandler,+null);
}

private+delegate+void+AsyncMethodCaller(MailMessage+message);

private+void+SendMailInSeperateThread(MailMessage+message)
{
++++try
++++{
++++++++SmtpClient+client+=+new+SmtpClient();
++++++++client.Timeout+=+20000;+//+20+second+timeout...+why+more?
++++++++client.Send(message);
++++++++client.Dispose();
++++++++message.Dispose();

++++++++//+If+you+have+a+flag+checking+to+see+if+an+email+was+sent,+set+it+here
++++++++//+Pass+more+parameters+in+the+delegate+if+you+need+to...
++++}
++++catch+(Exception+e)
++++{
+++++++++//+This+is+very+necessary+to+catch+errors+since+we+are+in
+++++++++//+a+different+context+&+thread
+++++++++Elmah.ErrorLog.GetDefault(null).Log(new+Error(e));
++++}
}

private+void+AsyncCallback(IAsyncResult+ar)
{
++++try
++++{
++++++++AsyncResult+result+=+(AsyncResult)ar;
++++++++AsyncMethodCaller+caller+=+(AsyncMethodCaller)result.AsyncDelegate;
++++++++caller.EndInvoke(ar);
++++}
++++catch+(Exception+e)
++++{
++++++++Elmah.ErrorLog.GetDefault(null).Log(new+Error(e));
++++++++Elmah.ErrorLog.GetDefault(null).Log(new+Error(new+Exception("Emailer+-+This+hacky+asynccallback+thing+is+puking,+serves+you+right.")));
++++}
}|code-block|syntax|javascript|688950|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|Q|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|R|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|S|8|@]|9|@]|A|$K|L]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

There was a lot of good advice that I upvoted here... such as making sure to remember to use IDisposable (i totally didn't know). I also realized how important it is to manually catch errors when in another thread since there is no context -- I have been working on a theory that I should just let ELMAH handle everything. Also, further exploration made me realize I was forgetting to use IDisposable on mailmessage, too.

In response to Richard, although I see that the threading solution can work (as suggested in my first example) as long as i'm catching the errors... there's still something scary about the fact that IIS completely explodes if that error isn't caught. That tells me that ASP.NET/IIS never meant for you to do that... which is why i'm leaning towards continuing to use .BeginInvoke/delegates instead since that doesn't mess up IIS when something goes wrong and seems to be more popular in ASP.NET.

In response to ASawyer, I was totally surprised that there was a .SendAsync built into the SMTP client. I played with that solution for a while, but it doesn't seem to do the trick for me. Although I can skip through the client of code that does SendAsync, the page still "waits" until the SendCompleted event is done. My goal was to have the user and the page move forward while the email is getting sent in the background. I have a feeling that I might still be doing something wrong... so if someone comes by this they might want to try it themselves.

Here's my full solution for how I sent emails 100% asynchronously in addition with ELMAH.MVC error logging. I decided to go with an expanded version of example 2:

<pre><code>public void SendThat(MailMessage message)
{
 AsyncMethodCaller caller = new AsyncMethodCaller(SendMailInSeperateThread);
 AsyncCallback callbackHandler = new AsyncCallback(AsyncCallback);
 caller.BeginInvoke(message, callbackHandler, null);
}

private delegate void AsyncMethodCaller(MailMessage message);

private void SendMailInSeperateThread(MailMessage message)
{
 try
 {
 SmtpClient client = new SmtpClient();
 client.Timeout = 20000; // 20 second timeout... why more?
 client.Send(message);
 client.Dispose();
 message.Dispose();

 // If you have a flag checking to see if an email was sent, set it here
 // Pass more parameters in the delegate if you need to...
 }
 catch (Exception e)
 {
 // This is very necessary to catch errors since we are in
 // a different context &amp; thread
 Elmah.ErrorLog.GetDefault(null).Log(new Error(e));
 }
}

private void AsyncCallback(IAsyncResult ar)
{
 try
 {
 AsyncResult result = (AsyncResult)ar;
 AsyncMethodCaller caller = (AsyncMethodCaller)result.AsyncDelegate;
 caller.EndInvoke(ar);
 }
 catch (Exception e)
 {
 Elmah.ErrorLog.GetDefault(null).Log(new Error(e));
 Elmah.ErrorLog.GetDefault(null).Log(new Error(new Exception("Emailer - This hacky asynccallback thing is puking, serves you right.")));
 }
}
</code></pre>

blocks|key|472792|text|使用这种方式-|type|unstyled|depth|inlineStyleRanges|entityRanges|data|472793|private+void+email(object+parameters)
++++{
++++++++Array+arrayParameters+=+new+object[2];
++++++++arrayParameters+=+(Array)parameters;
++++++++string+Email+=+(string)arrayParameters.GetValue(0);
++++++++string+subjectEmail+=+(string)arrayParameters.GetValue(1);
++++++++if+(Email+!=+"Email@email.com")
++++++++{
++++++++++++OnlineSearch+OnlineResult+=+new+OnlineSearch();
++++++++++++try
++++++++++++{
++++++++++++++++StringBuilder+str+=+new+StringBuilder();
++++++++++++++++MailMessage+mailMessage+=+new+MailMessage();

++++++++++++++++//here+we+set+the+address
++++++++++++++++mailMessage.From+=+fromAddress;
++++++++++++++++mailMessage.To.Add(Email);//here+you+can+add+multiple+emailid
++++++++++++++++mailMessage.Subject+=+"";
++++++++++++++++//here+we+set+add+bcc+address
++++++++++++++++//mailMessage.Bcc.Add(new+MailAddress("bcc@site.com"));
++++++++++++++++str.Append("<html>");
++++++++++++++++str.Append("<body>");
++++++++++++++++str.Append("<table+width=720+border=0+align=left+cellpadding=0+cellspacing=5>");

++++++++++++++++str.Append("</table>");
++++++++++++++++str.Append("</body>");
++++++++++++++++str.Append("</html>");
++++++++++++++++//To+determine+email+body+is+html+or+not
++++++++++++++++mailMessage.IsBodyHtml+=+true;
++++++++++++++++mailMessage.Body+=+str.ToString();
++++++++++++++++//file+attachment+for+this+e-mail+message.
++++++++++++++++Attachment+attach+=+new+Attachment();
++++++++++++++++mailMessage.Attachments.Add(attach);
++++++++++++++++mailClient.Send(mailMessage);
++++++++++++}

++++}


++protected+void+btnEmail_Click(object+sender,+ImageClickEventArgs+e)
++++{
++++++++try
++++++++{
++++++++++++string+To+=+txtEmailTo.Text.Trim();
++++++++++++string[]+parameters+=+new+string[2];
++++++++++++parameters[0]+=+To;
++++++++++++parameters[1]+=+PropCase(ViewState["StockStatusSub"].ToString());
++++++++++++Thread+SendingThreads+=+new+Thread(email);
++++++++++++SendingThreads.Start(parameters);
++++++++++++lblEmail.Visible+=+true;
++++++++++++lblEmail.Text+=+"Email+Send+Successfully+";
++++++++}|code-block|syntax|javascript|472794|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Use this way-

<pre><code>private void email(object parameters)
 {
 Array arrayParameters = new object[2];
 arrayParameters = (Array)parameters;
 string Email = (string)arrayParameters.GetValue(0);
 string subjectEmail = (string)arrayParameters.GetValue(1);
 if (Email != "Email@email.com")
 {
 OnlineSearch OnlineResult = new OnlineSearch();
 try
 {
 StringBuilder str = new StringBuilder();
 MailMessage mailMessage = new MailMessage();

 //here we set the address
 mailMessage.From = fromAddress;
 mailMessage.To.Add(Email);//here you can add multiple emailid
 mailMessage.Subject = "";
 //here we set add bcc address
 //mailMessage.Bcc.Add(new MailAddress("bcc@site.com"));
 str.Append("&lt;html&gt;");
 str.Append("&lt;body&gt;");
 str.Append("&lt;table width=720 border=0 align=left cellpadding=0 cellspacing=5&gt;");

 str.Append("&lt;/table&gt;");
 str.Append("&lt;/body&gt;");
 str.Append("&lt;/html&gt;");
 //To determine email body is html or not
 mailMessage.IsBodyHtml = true;
 mailMessage.Body = str.ToString();
 //file attachment for this e-mail message.
 Attachment attach = new Attachment();
 mailMessage.Attachments.Add(attach);
 mailClient.Send(mailMessage);
 }

 }


 protected void btnEmail_Click(object sender, ImageClickEventArgs e)
 {
 try
 {
 string To = txtEmailTo.Text.Trim();
 string[] parameters = new string[2];
 parameters[0] = To;
 parameters[1] = PropCase(ViewState["StockStatusSub"].ToString());
 Thread SendingThreads = new Thread(email);
 SendingThreads.Start(parameters);
 lblEmail.Visible = true;
 lblEmail.Text = "Email Send Successfully ";
 }
</code></pre>

blocks|key|472832|text|从.NET+4.5开始，SmtpClient实现了异步可等待方法SendMailAsync。因此，异步发送电子邮件的步骤如下：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|472833|public+async+Task+SendEmail(string+toEmailAddress,+string+emailSubject,+string+emailMessage)
{
++++var+message+=+new+MailMessage();
++++message.To.Add(toEmailAddress);

++++message.Subject+=+emailSubject;
++++message.Body+=+emailMessage;

++++using+(var+smtpClient+=+new+SmtpClient())
++++{
++++++++await+smtpClient.SendMailAsync(message);
++++}
}+|code-block|syntax|javascript|472834|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/hh193922%2528v=vs.110%2529.aspx^0|W|D|W|D|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@$9|V|A|W|1|X]]|E|$]]|$1|F|3|G|5|H|7|Y|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]]]

As of .NET 4.5 SmtpClient implements async awaitable method 
<a href="http://msdn.microsoft.com/en-us/library/hh193922%28v=vs.110%29.aspx" rel="noreferrer"><code>SendMailAsync</code></a>.
As a result, to send email asynchronously is as the following:

<pre><code>public async Task SendEmail(string toEmailAddress, string emailSubject, string emailMessage)
{
 var message = new MailMessage();
 message.To.Add(toEmailAddress);

 message.Subject = emailSubject;
 message.Body = emailMessage;

 using (var smtpClient = new SmtpClient())
 {
 await smtpClient.SendMailAsync(message);
 }
} 
</code></pre>

When a user registers on my website, I don't see why I need to make him "wait" for the smtp to go through so that he gets an activation email.

I decided I want to launch this code asynchronously, and it's been an adventure.

Lets imagine I have a method, such as:

<pre><code>private void SendTheMail() { // Stuff }
</code></pre>

My first though.. was threading. I did this:

<pre><code>Emailer mailer = new Emailer();
Thread emailThread = new Thread(() =&gt; mailer.SendTheMail());
emailThread.Start();
</code></pre>

This works... until I decided to test it for error-handling capability. I purposely broke the SMTP server address in my web.config and tried it. The scary result was that IIS basically BARFED with an unhandled exception error on w3wp.exe (it was a windows error! how extreme...) ELMAH (my error logger) did NOT catch it AND IIS was restarted so anyone on the website had their session erased. Completely unacceptable result!

My next thought, was to do some research on Asynchronous delegates. This seems to work better because exceptions are being handled within the asynch delegate (unlike the thread example above). However, i'm concerned if i'm doing it wrong or maybe I'm causing memory leaks.

Here's what i'm doing:

<pre><code>Emailer mailer = new Emailer();
AsyncMethodCaller caller = new AsyncMethodCaller(mailer.SendMailInSeperateThread);
caller.BeginInvoke(message, email.EmailId, null, null);
// Never EndInvoke... 
</code></pre>

Am I doing this right?

Proper way to asynchronously send an email in ASP.NET... (am i doing it right?)

服务器

当用户在我的网站上注册时，我不明白为什么我需要让他“等待”smtp通过，这样他才能收到激活电子邮件。我决定异步启动这段代码，这是一次冒险。假设我有一个方法，比如：private void SendTheMail() { // Stuff }我的第一次..是线程化。我这样做了：Emailer mailer = new E...

问在ASP.NET中异步发送电子邮件的正确方法...(我做得对吗？)
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