Sending mail using SmtpClient in .net
I am unable to send the mail using smtp client. here is the code:
SmtpClient client=new SmtpClient("Host");
client.Credentials=new NetworkCredential("username", "password"开发者_运维问答);
MailMessage mailMessage = new MailMessage();
mailMessage.from="sender@gmail.com";
mailMessage.To.Add("recipient@gmail.com");
mailMessage.body="body";
mailMessage.subject="subject";
client.Send(mailMessage);
The problem is that when I use this code in ASP.NET application, I do not receive any mails. When in asp.net I change the from mail address to username given in NetworkCredential, I receive mails.
But in C# windows application, I can get emails, even if sender's email address is not valid.
I figured out that setting the SmtpClient Credentials property before setting the <html><span class="diff-delete">UseDefaultCredentials = false</span></html>. UseDefaultCredentials = false causes the credentials to be ignored.
Fails:
SmtpClient smtp = new SmtpClient;
smtp.Credentials = new NetworkCredential("user","pass");
smtp.UseDefaultCredentials = false;
Works:
SmtpClient smtp = new SmtpClient;
smtp.UseDefaultCredentials = false;
smtp.Credentials = new NetworkCredential("user","pass");
Go figure.
** UPDATE **
The reason the order is important here is that the setter on the UseDefaultCredentials property actually sets the Credentials to null via the decompiled code:
/// <summary>Gets or sets a <see cref="T:System.Boolean" /> value that controls whether the <see cref="P:System.Net.CredentialCache.DefaultCredentials" /> are sent with requests.</summary>
/// <returns>
/// <see langword="true" /> if the default credentials are used; otherwise <see langword="false" />. The default value is <see langword="false" />.</returns>
/// <exception cref="T:System.InvalidOperationException">You cannot change the value of this property when an e-mail is being sent.</exception>
public bool UseDefaultCredentials
{
get
{
return this.transport.Credentials is SystemNetworkCredential;
}
set
{
if (this.InCall)
throw new InvalidOperationException(SR.GetString("SmtpInvalidOperationDuringSend"));
this.transport.Credentials = value ? (ICredentialsByHost) CredentialCache.DefaultNetworkCredentials : (ICredentialsByHost) null;
}
}
The short answer : Do not use .net the internal SMTP client class - use MailKit.
The long answer :
- It is marked as obsolete in MS docs
[System.Obsolete("SmtpClient and its network of types are poorly designed, we strongly recommend you use https://github.com/jstedfast/MailKit and https://github.com/jstedfast/MimeKit instead")] public class SmtpClient : IDisposable
- Use the oss lib MailKit.
- Elaboration : Because you will face its deficiencies sooner rather than later. Read here or read around the internet.
- Here is an example for sending plain messages and multipart messages.
I intentionally did not copy-paste the examples from the docs here because the documentation may change over time and it is better to read .
It means your mail server does not allow Mail-Relay. Your mail server only allows you to send mail from authenticated email-id as username. Generally this is done to prevent mails being sent as different identities other than the authenticated one.
Try this :
MailMessage mail = new MailMessage("emailfrom","emailto");
mail.From = new MailAddress("emailfrom");
mail.Subject = txtsbjct.Text;
string Body = txtmsg.Text;
mail.Body = Body;
mail.IsBodyHtml = true;
SmtpClient smtp = new SmtpClient();
smtp.Host = "smtp.gmail.com"; //Or Your SMTP Server Address
smtp.Credentials = new System.Net.NetworkCredential("youremail", "yourpassword");
smtp.EnableSsl = true;
smtp.Send(mail);
txtemail.Text = "";
txtmsg.Text = "";
txtsbjct.Text = "";
Label1.Text = "your email has been send";
mail = null;
smtp = null;
void sendEmail(string strFrom
, string strTo
, string strSubject
, string strBody)
{
MailMessage objMailMessage = new MailMessage();
System.Net.NetworkCredential objSMTPUserInfo =
new System.Net.NetworkCredential();
SmtpClient objSmtpClient = new SmtpClient();
try
{
objMailMessage.From = new MailAddress(strFrom);
objMailMessage.To.Add(new MailAddress(strTo));
objMailMessage.Subject = strSubject;
objMailMessage.Body = strBody;
objSmtpClient = new SmtpClient("172.0.0.1"); /// Server IP
objSMTPUserInfo = new System.Net.NetworkCredential
("User name", "Password","Domain");
objSmtpClient.Credentials = objSMTPUserInfo;
objSmtpClient.UseDefaultCredentials = false;
objSmtpClient.DeliveryMethod = SmtpDeliveryMethod.Network;
objSmtpClient.Send(objMailMessage);
}
catch (Exception ex)
{ throw ex; }
finally
{
objMailMessage = null;
objSMTPUserInfo = null;
objSmtpClient = null;
}
}
加载中,请稍侯......
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