发送邮件发送异步

Question

我在使用 C# 和 sendmail 异步时遇到了一个奇怪的问题。 当我使用正常的发送方法时，一切正常，我的电子邮件正在发送到正确的 SMTP 服务器。但是当我使用 SendAsync-Method 时它不起作用。

mailClient.SendCompleted += SendCompleted;

private static void SendCompleted (object sender, AsyncCompletedEventArgs e)
{
  string token = (string) e.UserState;

  if (e.Cancelled)
  {
    MessageBox.Show (string.Format ("{0}\n\"{1}\"", Application.Current.FindResource ("MailCannotSend"), token), LogFile.MSGBOX_ERROR, MessageBoxButton.OK, MessageBoxImage.Error);
    return;
  }

  MessageBox.Show (e.Error != null ? string.Format ("{0}\n\"{1}\"", e.Error, token) : "Complete!", LogFile.MSGBOX_ERROR, MessageBoxButton.OK, MessageBoxImage.Error);
}

SendAsync-Method 总是在 e.Cancelled 中运行，没有任何异常或错误。我真的不知道为什么。

有人给点小费吗？谢谢！

更新

这里是完整的代码：

public void InitClient ()
{
  try
  {
    mailClient = new SmtpClient (SettingsHelper.TailSettings.AlertSettings.SmtpSettings.SmtpServerName, SettingsHelper.TailSettings.AlertSettings.SmtpSettings.SmtpPort)
    {
      UseDefaultCredentials = false,
      Timeout = 30000,
      DeliveryMethod = SmtpDeliveryMethod.Network
    };
    string decryptPassword = StringEncryption.Decrypt (SettingsHelper.TailSettings.AlertSettings.SmtpSettings.Password, LogFile.ENCRYPT_PASSPHRASE);
    NetworkCredential authInfo = new NetworkCredential (SettingsHelper.TailSettings.AlertSettings.SmtpSettings.LoginName, decryptPassword);
    mailClient.Credentials = authInfo;
    mailClient.SendCompleted += SendCompleted;

    if (SettingsHelper.TailSettings.AlertSettings.SmtpSettings.SSL)
      mailClient.EnableSsl = true;
    if (SettingsHelper.TailSettings.AlertSettings.SmtpSettings.TLS)
      ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls;

    MailAddress from = new MailAddress (SettingsHelper.TailSettings.AlertSettings.SmtpSettings.FromAddress);
    MailAddress to = new MailAddress (SettingsHelper.TailSettings.AlertSettings.EMailAddress);

    mailMessage = new MailMessage (from, to)
    {
      Subject = SettingsHelper.TailSettings.AlertSettings.SmtpSettings.Subject,
      SubjectEncoding = System.Text.Encoding.UTF8,
      BodyEncoding = System.Text.Encoding.UTF8,
      IsBodyHtml = false
    };
}
  catch (Exception ex)
  {
    ErrorLog.WriteLog (ErrorFlags.Error, GetType ( ).Name, string.Format ("{1}, exception: {0}", ex, System.Reflection.MethodBase.GetCurrentMethod ( ).Name));
  }
}

/// <summary>
/// Send E-Mail
/// </summary>
/// <param name="userToken">User token</param>
/// <param name="bodyMessage">Message to be send</param>
public void SendMail (string userToken, string bodyMessage = null)
{
  try
  {
    string userState = userToken;

    if (bodyMessage != null)
      mailMessage.Body = bodyMessage;

    if (String.Compare (userState, "testMessage", StringComparison.Ordinal) == 0)
      mailMessage.Body = string.Format ("Testmail from {0}", LogFile.APPLICATION_CAPTION);

    mailClient.SendAsync (mailMessage, userToken);

    if (String.Compare (userState, "testMessage", StringComparison.Ordinal) == 0)
      return;
}
  catch (Exception ex)
  {
    ErrorLog.WriteLog (ErrorFlags.Error, GetType ( ).Name, string.Format ("{1}, exception: {0}", ex, System.Reflection.MethodBase.GetCurrentMethod ( ).Name));
  }
}

Answer 1

SendAsync 是异步的，它将在未来完成。显然，您的调用 SendMail 结束的方法的范围 before SendCompleted 被触发。例如，控制台应用程序可能在您有机会处理此事件并处理异步操作完成之前就结束了。

任何进一步的建议将取决于您的应用程序的执行环境是什么：ASP.NET、WCF、控制台、WinForms、WPF 等。