System.Net.Mail

Use Simple Mail Transfer Protocol SMTP to send mail asynchronously

To implement SMTP to send mail, you need to understand these classes

SmtpClient: use the profile settings to initialize a new instance of the SmtpClient class.

It contains the following properties:

Host: set the host name or host IP used for SMTP service;

Port: set the port used for SMTP service (generally set to 25);

Credentials: authentication;

Send: send mail directly;

SendAsync: send messages asynchronously (calling threads are not blocked).

MailMessage: indicates an email.

It contains the following properties:

Attachment: indicates a file attachment;

CC: CC;

Subject: subject;

From: from

Priority: priority;

Body: body;

BodyEncoding:Content-type.

In addition, the SmtpClient class does not have a Finalize method, so the application must call Dispose To explicitly release resources.

 1 static bool mailsend = true;
 2  public async Task Send(object sender, EventArgs e)
 3         {
 4           
 5             SmtpClient smtp = new SmtpClient();//item base  SMPTClient object
 6             smtp.EnableSsl = false;//Not enabled SSL encryption
 7             smtp.Host = "00.000.00.000";//Server here IP
 8             smtp.Port = 25;//Port fixed to 25
 9             //smtp.Credentials = new NetworkCredential("user@.com","password");//Authenticate users  
10             MailMessage msg = new MailMessage();//item base  Message object
11             msg.Priority = MailPriority.High;//Message priority
12             msg.To.Add("user@foxmail.com");//Addressee
13            // msg.CC.Add("user@163.com");//CC
14             msg.Bcc.Add("user@qq.com");//bcc
15             string fileName = "";
16             var na = Request.Files.AllKeys;//Front end HTTP Requested documents
17             foreach (var item in na)
18             {
19                 HttpPostedFileBase file = Request.Files[item] as HttpPostedFileBase;
20                 fileName = Path.GetFullPath(file.FileName);
21             }
22             Attachment attach = new Attachment(fileName);//Pay file path to Attachment Instanced objects for
23             ContentDisposition dispo = attach.ContentDisposition;//Get information and read and write attachments
24             dispo.CreationDate = System.IO.File.GetCreationTime(fileName);
25             dispo.ModificationDate = System.IO.File.GetLastWriteTime(fileName);
26             dispo.ReadDate = System.IO.File.GetLastAccessTime(fileName);
27             msg.Attachments.Add(attach);//Add attachment to message
28             msg.From = new MailAddress("SpadesQ@sea.com", "It's you.");//Sender alias
29             msg.Subject = "I learned. How about you?";
30             msg.SubjectEncoding = System.Text.Encoding.UTF8;
31             msg.Body = "Wait for the next one";
32             msg.BodyEncoding = System.Text.Encoding.UTF8;
33             smtp.SendCompleted += new SendCompletedEventHandler(client_SendCompleted);
34             string userState = "Task one";
35             smtp.SendAsync(msg, userState);//Send asynchronously, otherwise the thread will block
36             if (mailsend==false) //Modifiable on callback mailsend Value to cancel
37             {
38                 smtp.SendAsyncCancel();
39             }
40             Response.Write("Already issued");
41         }
42         
43          void client_SendCompleted(object sender, AsyncCompletedEventArgs e)
44         {
45             string token =(string)e.UserState;
46             if (e.Cancelled)
47             {
48                 Response.Write(string.Format("{0} Send canceled.",token));
49             }
50             if (e.Error !=null)
51             {
52                 Response.Write(string.Format("[{0}] {1}", token, e.Error.ToString()));
53             }
54             else
55             {
56                 Response.Write("Message Send.");
57             }
58             mailsend = true;
59         }

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