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what is the difference between these two methods?

system.net.mail.smtpclient has two methods for which I am very confused.
1 . SendAsync(MailMessage, Object)
Sends the specified e-mail message to an SMTP server for delivery. This method does not block the calling thread and allows the caller to pass an object to the method that is invoked when the operation completes. -MSDN
2 . SendMailAsync(MailMessage)
Sends the specified message to an SMTP server for delivery as an asynchronous operation. -MSDN
Notice that the names of two methods are different so it is not an overload. What exactly is the difference here?
I am looking for very clear answer as the description given by MSDN for both methods is very ambiguous (at least for me it is.)

The difference is one SendMailAsync uses the new async/await technology and the other uses the old callback technology. And more importantly, the Object that's passed is simply passed into the event handler as the userState when the method completes.

Firstly, they both work asynchronously.
However, SendAsync has existed since .NET 2. In order to maintain backwards compatiblity whilst supporting the new Tasks system SendMailAsync was added.
SendMailAsync returns a Task rather than void and allows the SmtpClient to support the new async and await functionality if required.

//SendAsync
public class MailHelper
{
public void SendMail(string mailfrom, string mailto, string body, string subject)
{
MailMessage MyMail = new MailMessage();
MyMail.From = new MailAddress(mailfrom);
MyMail.To.Add(mailto);
MyMail.Subject = subject;
MyMail.IsBodyHtml = true;
MyMail.Body = body;
MyMail.Priority = MailPriority.Normal;
SmtpClient smtpMailObj = new SmtpClient();
/*Setting*/
object userState = MyMail;
smtpMailObj.SendCompleted += new SendCompletedEventHandler(SmtpClient_OnCompleted);
try
{
smtpMailObj.SendAsync(MyMail, userState);
}
catch (Exception ex) { /* exception handling code here */ }
}
public static void SmtpClient_OnCompleted(object sender, AsyncCompletedEventArgs e)
{
//Get the Original MailMessage object
MailMessage mail = (MailMessage)e.UserState;
//write out the subject
string subject = mail.Subject;
if (e.Cancelled)
{
Console.WriteLine("Send canceled for mail with subject [{0}].", subject);
}
if (e.Error != null)
{
Console.WriteLine("Error {1} occurred when sending mail [{0}] ", subject, e.Error.ToString());
}
else
{
Console.WriteLine("Message [{0}] sent.", subject);
}
}
//
}
//SendMailAsync
public class MailHelper
{
//
public async Task<bool> SendMailAsync(string mailfrom, string mailto, string body, string subject)
{
MailMessage MyMail = new MailMessage();
MyMail.From = new MailAddress(mailfrom);
MyMail.To.Add(mailto);
MyMail.Subject = subject;
MyMail.IsBodyHtml = true;
MyMail.Body = body;
MyMail.Priority = MailPriority.Normal;
using (SmtpClient smtpMailObj = new SmtpClient())
{
/*Setting*/
try
{
await smtpMailObj.SendMailAsync(MyMail);
return true;
}
catch (Exception ex) { /* exception handling code here */ return false; }
}
}
}

SendMailAsync a simple TAP wrapper for SendAsync
More info: Are the SmtpClient.SendMailAsync methods Thread Safe?

how to send mails asynchronous? [duplicate]

This question already has answers here:
Asynchronously sending Emails in C#?
(11 answers)
Closed 9 years ago.
namespace Binarios.admin
{
public class SendEmailGeral
{
public SmtpClient client = new SmtpClient("smtp.gmail.com", 587);
public MailMessage msg = new MailMessage();
public void Enviar(string sendFrom, string sendTo, string subject, string body)
{
string pass = "12345";
System.Net.NetworkCredential smtpCreds = new System.Net.NetworkCredential(sendFrom, pass);
//setup SMTP Host Here
client.UseDefaultCredentials = false;
client.Credentials = smtpCreds;
client.EnableSsl = true;
MailAddress to = new MailAddress(sendTo);
MailAddress from = new MailAddress(sendFrom);
msg.IsBodyHtml = true;
msg.Subject = subject;
msg.Body = body;
msg.From = from;
msg.To.Add(to);
client.Send(msg);
}
}
}
I've this code, but i'd like to improve it in way that i could send mails asynchronous.
Could you suggest any idea to improve this piece of code or other way to do it.
I've tried asynchronous properties that visual studio suggested but couldn't use them.

SmtpClient allows you to send asynchronously, and uses events to notify you when the send completes. This can be unweildy to use, so you can create an extension method to return a Task instead:
public static Task SendAsync(this SmtpClient client, MailMessage message)
{
TaskCompletionSource<object> tcs = new TaskCompletionSource<object>();
Guid sendGuid = Guid.NewGuid();
SendCompletedEventHandler handler = null;
handler = (o, ea) =>
{
if (ea.UserState is Guid && ((Guid)ea.UserState) == sendGuid)
{
client.SendCompleted -= handler;
if (ea.Cancelled)
{
tcs.SetCanceled();
}
else if (ea.Error != null)
{
tcs.SetException(ea.Error);
}
else
{
tcs.SetResult(null);
}
}
};
client.SendCompleted += handler;
client.SendAsync(message, sendGuid);
return tcs.Task;
}
To get the result of the send task you can use ContinueWith:
Task sendTask = client.SendAsync(message);
sendTask.ContinueWith(task => {
if(task.IsFaulted) {
Exception ex = task.InnerExceptions.First();
//handle error
}
else if(task.IsCanceled) {
//handle cancellation
}
else {
//task completed successfully
}
});

Wild guess, but SendAsync might do the job!

Change your code from:
client.Send(msg);
To:
client.SendAsync(msg);
more details
link1
link2

c# - SMTP Async - callback in web service to client page

I had a web service to send email in C#
[WebMethod]
public string sendEmail()
{
MailMessage mail = new MailMessage();
SmtpClient smtpsvr = new SmtpClient("smtp.gmail.com");
// mail settings
// smtpsvr settings
smtpsvr.SendCompleted += new SendCompletedEventHandler(sentCompleteCallBack);
try
{
smtpsvr.SendAsync(mail, "Email 1");
return "sent"; //this return only indicate email has been sent out
}
catch (Exception)
{
return "failed";
}
}
private void sentCompleteCallBack(object sender, AsyncCompletedEventArgs e)
{
if (e.Error != null) //error
{
sendResult = "email failed " + (string)e.UserState;
}
else
{ //this result, indicate the process of sending email has been completed
sendResult = "email sent " + (string)e.UserState;
}
// ??? haw to pass sendResult value to client page
}
I tried using properties string, class string to get sendResult value; but at the end in client page (aspx), only got empty/null. I only can get string sendEmail() value.
How to pass back the sendResult value to client ?
Thanks so much for the help !
/**********/
edited
May be I have to change the code like this ? (still using sendAsync()
[WebMethod]
public string sendEmail()
{
MailMessage mail = new MailMessage();
SmtpClient smtpsvr = new SmtpClient("smtp.gmail.com");
//mail settings
//smtpsvr settings
smtpsvr.SendCompleted += new SendCompletedEventHandler(sentCompleteCallBack);
try
{
smtpsvr.SendAsync(mail, "email 1");
return "sent";
}
catch (Exception)
{
return "failed";
}
}
private void sentCompleteCallBack(object sender, AsyncCompletedEventArgs e)
{
if (e.Error != null) //error
{
//write to DB_email_status = "failed"
}
else
{
//write to DB_email_status = "success"
}
}
in client side page (aspx) :
(1) call web service to send email.
(2) get email sent string value from sendEmail() method.
(3) button_onclick : view/get data from DB_email_status.
(???) is this case achieveable ?
(!!!) Thanks so much.

If you are using stateless protocol as in HTTP , then the server(Web service) can give only one response to the client. So, there is no way for the WebService to send details of the Async results to the client unless the client probes it again for status.
IMO, your best bet is to use .Send() instead of .SendAsync(). You can use Timeout property to prevent the method from hanging.

Why dont you just pass in a bool as return value in your SendEmail method like below
bool sentEmail()
{
bool isValid = false;
try
{
//if email successful
isValid = true
}
catch(Exception ex)
{
//Email Fails
isValid = false;
}
return isValid;
}

or using send() and thread.
[WebMethod]
public bool sendEmail()
{
//mail settings
//smtp settings
try
{
smtp.Send(mail);
return true;
}
catch
{
return false;
}
client page (aspx)
private void send()
{
Thread.Sleep(100;
//call web service: sendEmail()
if true
{ label.Text = "sent"} else {label.Text = "fail"}
}
private void button_Onclick(...)
{
Thread t = new Thread (send);
t.Start();
t.Join();
}
will behave similiar like sendAsync(), but easier to get return value.

Sending a list of mails with SmtpClient

I use SendCompletedEventHandler of SmtpClient when sending a list of emails.
The SendCompletedEventHandler is only called when have already sent all emails in the list.
I expexted, that SendCompletedEventHandler is called when an email is sent.
Is there something wrong in my code?
public void SendAllNewsletters(List<string> recipients)
{
string mailText = "My Text";
foreach(string recipient in recipients)
{
//if this loop takes 10min then the first call to
//SendCompletedCallback is after 10min
SendNewsletter(mailText,recipient);
}
}
public bool SendNewsletter(string mailText , string emailaddress)
{
SmtpClient sc = new SmtpClient(_smtpServer, _smtpPort);
System.Net.NetworkCredential SMTPUserInfo = new System.Net.NetworkCredential(_smtpuser, _smtppassword);
sc.Credentials = SMTPUserInfo;
sc.SendCompleted += new SendCompletedEventHandler(SendCompletedCallback);
MailMessage mm = null;
mm = new MailMessage(_senderemail, emailaddress );
mm.IsBodyHtml = true;
mm.Priority = MailPriority.Normal;
mm.Subject = "Something";
mm.Body = mailText ;
mm.SubjectEncoding = Encoding.UTF8;
mm.BodyEncoding = Encoding.UTF8;
//Mail
string userState = emailaddress;
sc.SendAsync(mm, userState);
return true;
}
public void SendCompletedCallback(object sender, AsyncCompletedEventArgs e)
{
// Get the unique identifier for this asynchronous operation.
String token = (string)e.UserState;
if (e.Error != null)
{
_news.SetNewsletterEmailsisSent(e.UserState.ToString(), _newslettername, false, e.Error.Message);
}
else
{
_news.SetNewsletterEmailsisSent(e.UserState.ToString(), _newslettername, true, string.Empty);
}
}

You are creating a new instance of SmtpClient each and every time (and then re-assigning the handler). Use a static variable with a bigger scope.

It works as expected on my machine except that the constructor of MailMessage throw a format exception because "My Tex" is not a valid email address. The first argument is the email address of the sender.
As Josh Stodola points out, you should cache the SmtpClient for the life of this class rather than creating another one for each call. If you don't cache the SmtpClient, then you should add the following line to the end of your SendCompletedCallback (preferably in a finally block):
((SmtpClient)sender).SendCompleted -= SendCompletedCallback;
If this doesn't help you, perhaps you could post more details - such as what is the data in the event args that do get called?

c# sending mail from window form not triggering

I'm having some wierd behaviour in my WinForm application coded in c#.
in my:
private void buttonSave_Click(object sender, EventArgs e)
Im calling my function:
functions.sendStatusEmail();
The weird thing is that, when I press the Save button then email send is not triggered. But if I close my application the mail is handle and sent.
Have I missed something or do one need to trigger som application event manually to have run the sendout.
( I tried using client.SendAsync(mail,null); then it triggerd at click but the mail was empty)
Thanks in advance
--
Edit: code expamples
private void buttonSave_Click(object sender, EventArgs e)
{
// checks if a ticket is active
if (workingTicketId > 0)
{
// update ticket information
functions.updateTicketInfo(workingTicketId, comboBoxPriority.SelectedIndex,
comboBoxStatus.SelectedIndex, textBoxComment.Text);
// gives feedback
labelFeedback.Text = "Updated";
// updates the active ticket list
populateActiveTicketList();
// marks working ticket row in list
dataGridActiveTicketList.Rows[workingGridIndex].Selected = true;
// checks for change of ticket status
if (comboBoxStatus.SelectedIndex != workingTicketStatus)
{
// checks if contact person exists
if (labelContactPersonValue.Text.ToString() != "")
{
// sends email to contact person
functions.sendStatusEmail(labelContactPersonValue.Text, comboBoxStatus.SelectedIndex, workingTicketId, textBoxDescription.Text);
}
// updates working ticket status
workingTicketStatus = comboBoxStatus.SelectedIndex;
}
}
}
and the send email function:
// sends a status email to contact person
// returns noting
public void sendStatusEmail(string email, int newStatus, int ticketId, string ticketText)
{
// defines variables
string emailSubject;
string emailBody;
// some exkluded mailcontent handling
// sends mail
MailMessage mail = new MailMessage("myFromEmail#hidden.com",email,emailSubject,emailBody);
SmtpClient client = new SmtpClient(ConfigurationManager.AppSettings["MailSMTP"]);
mail.IsBodyHtml = true;
client.Send(mail);
// dispose
mail.Dispose();
}

Cannot understand why it would not work. I used below function and it sends the email successfully:
public static bool SendEmail (string smtpServer, string fromAddress, string fromDisplayName,
string toAddress, string subject, string contents, bool important) {
MailAddress from = new MailAddress (fromAddress, fromDisplayName);
MailPriority priority = important ? MailPriority.High : MailPriority.Normal;
MailMessage m = new MailMessage {
From = from,
Subject = subject,
Body = contents,
Priority = priority,
IsBodyHtml = false
};
MailAddress to = new MailAddress (toAddress);
m.To.Add (to);
SmtpClient c = new SmtpClient (smtpServer) { UseDefaultCredentials = false };
c.Send (m);
return true;
}
No offence but are you sure that it is closing the application which results in email being sent. Most of the times there is a delay between an email is sent and it is received because of the traffic on SMTP server. Try pressing that button and then wait for some time (3-4 minutes) and try refreshing your inbox during that time.

BTW, the SendAsync didnt work because you called mail.dispose() after the Async call.
The right way to do it in async would be,
private void button1_Click(object sender, EventArgs e)
{
MailMessage mail = new MailMessage("from#domain.com", "to#domain.com", "subj", "body");
SmtpClient client = new SmtpClient("SMTPHOST");
mail.IsBodyHtml = true;
client.SendCompleted += new
SendCompletedEventHandler(SendCompletedCallback);
client.SendAsync(mail,mail);//send the mail object itself as argument to callback
}
private void SendCompletedCallback(object sender, AsyncCompletedEventArgs e)
{
if (e.Cancelled)
{
//Mail sending is cancelled
}
if (e.Error != null)
{
//There is an error,e.Error will contain the exception
}
else
{
//Do any other success processing
}
((MailMessage)e.UserState).Dispose();//Dispose
}