我应该通过SMTP服务器发送电子邮件。此SMTP服务器需要身份验证。但是,如果我使用.NET SmtpClient的默认身份验证机制,则504 Unrecognized Authentication Type
身份验证将失败。
使用PuTTy时,我可以成功进行身份验证:
250 AUTH LOGIN PLAIN
AUTH LOGIN
334 VXNlcm5hbWU6
Some base64 encoded username
334 UGFzc3dvcmQ6
Some base64 encoded password
235 Authentication Successful
SmtpClient
使用的方法略有不同,其中用户名是通过AUTH LOGIN命令传递的:250 AUTH LOGIN PLAIN
AUTH LOGIN Some base64 encoded username
504 Unrecognized Authentication
MAIL FROM: ...
它似乎忽略了504,因为它正在发送MAIL FROM命令。
阅读internet上的一些资源,可以使用AUTH LOGIN命令发送用户名:
该问题很可能是在SMTP服务器方面,但是我无法控制它。
是否可以让SmtpClient单独发送命令?
样例代码
using (var client = new SmtpClient(_configuration.Host, _configuration.Port))
{
client.UseDefaultCredentials = false;
client.ServicePoint.MaxIdleTime = 1;
client.EnableSsl = false;
client.Credentials = new NetworkCredential(_configuration.Username, _configuration.Password, _configuration.Domain);
var from = new MailAddress(string.Format("{0}@{1}", _configuration.Sender, _configuration.Domain));
var to = new MailAddress(string.Format("{0}@{1}", to, _configuration.Domain));
var message = new MailMessage(from, to)
{
Body = body
};
client.Send(message);
}
DIY
只是为了好玩(而不是为了生产),我尝试进行自己的交流:
using (var connection = new TcpClient(_configuration.Host, _configuration.Port))
using (NetworkStream stream = connection.GetStream())
{
string header = Read(stream);
Reply(stream, "EHLO " + Environment.MachineName);
while (!Read(stream).ToUpperInvariant().Contains("AUTH LOGIN PLAIN"))
{
}
Reply(stream, "AUTH LOGIN");
string requestUsername = Read(stream);
Reply(stream, Convert.ToBase64String(Encoding.ASCII.GetBytes(_configuration.Username)));
string requestPassword = Read(stream);
Reply(stream, Convert.ToBase64String(Encoding.ASCII.GetBytes(_configuration.Password)));
string authSucces = Read(stream);
Reply(stream, string.Format("MAIL FROM: <{0}@{1}>", _configuration.Sender, _configuration.Domain));
string senderOk = Read(stream);
Reply(stream, string.Format("RCPT TO: <{0}@{1}>", to, _configuration.Domain));
string rcptOk = Read(stream);
Reply(stream, "DATA");
string sendData = Read(stream);
Reply(stream, body);
Reply(stream, string.Empty);
Reply(stream, ".");
Reply(stream, string.Empty);
stream.Close();
connection.Close();
}
private string Read(NetworkStream stream)
{
var data = new byte[1024];
int received = stream.Read(data, 0, data.Length);
string contents = Encoding.ASCII.GetString(data, 0, received);
return contents;
}
private void Reply(NetworkStream stream, string reply)
{
reply = reply + Environment.NewLine;
stream.Write(Encoding.ASCII.GetBytes(reply), 0, reply.Length);
stream.Flush();
}
这很好用。因此,这绝对是关于
SmtpClient
与实际Smtp服务器如何通信的。解决方法
事实证明,我们一直在与单独实现SMTP协议(protocol)的系统通信,但他们做错了。因此,我们决定自己进行通信,直到供应商确定其代码为止。幸运的是,它仅用于内部目的,并且沟通是可以预见的。我们正在使用DIY代码进行一些重构和清理。
最佳答案
我也遇到了Here is my solution/workaround问题:使用System.Web.Mail而不是System.Net.Mail发送电子邮件。我知道这不是最好的解决方案,因为该库已过时,但在供应商修复代码之前可能会有所帮助。
System.Web.Mail.MailMessage msg = new System.Web.Mail.MailMessage();
msg.Body = message.Body;
string smtpServer = "mail.business.it";
string userName = "username";
string password = "password";
int cdoBasic = 1;
int cdoSendUsingPort = 2;
if (userName.Length > 0)
{
msg.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpserver", smtpServer);
msg.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpserverport", 25);
msg.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendusing", cdoSendUsingPort);
msg.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate", cdoBasic);
msg.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendusername", userName);
msg.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendpassword", password);
}
msg.To = message.Destination;
msg.From = "me@domain.it";
msg.Subject = message.Subject;
msg.BodyFormat = MailFormat.Html;//System.Text.Encoding.UTF8;
SmtpMail.SmtpServer = smtpServer;
SmtpMail.Send(msg);