从web.config中膨胀时,SmtpClient不会进行身份验证

Question

使用system.net/mail web.config设置配置我的SmtpClient时,它无法发送电子邮件,其中"协议错误"最好由Base64编码和身份验证问题描述:

示例:
使用以下配置

<system.net>
    <mailSettings>
        <smtp from="email@server.com">
            <network host="servermail.outsourced.com"
                     port="2525" 
                     defaultCredentials="false" 
                     userName="username" 
                     password="password"/>
        </smtp>
    </mailSettings>
</system.net>

和守则:

var tmp = new SmtpClient();

MailMessage msg = new MailMessage();
msg.Subject = "test";
msg.From = new MailAddress("me@server.com");
msg.To.Add(new MailAddress("me@server.com"));
msg.Body = "test";
tmp.Send(msg);

生成错误消息:

System.Net.Mail.SmtpException: The server committed a protocol violation The server response was: UGFzc3dvcmQ6
   at System.Net.Mail.MailCommand.CheckResponse(SmtpStatusCode statusCode, String response)
   at System.Net.Mail.SmtpTransport.SendMail(MailAddress sender, MailAddressCollection recipients, String deliveryNotify, SmtpFailedRecipientException
& exception)
   at System.Net.Mail.SmtpClient.Send(MailMessage message)

但是,在下面的代码中,我手动设置了所有属性,代码运行无例外,并且已发送电子邮件.

var tmp2 = new SmtpClient("servermail.outsourced.com", 2525);
tmp2.Credentials = new NetworkCredential("username", "password");
tmp2.UseDefaultCredentials = false;

MailMessage msg = new MailMessage();
msg.Subject = "test";
msg.From = new MailAddress("me@server.com");
msg.To.Add(new MailAddress("me@server.com"));
msg.Body = "test";
tmp2.Send(msg);

Answer 1

我在 LINQPad 中针对我的 hMailServer 邮件服务器尝试了您的配置设置，效果很好。所以，我的猜测是，您正在通信的邮件服务器正在以意想不到的方式与客户端握手。当我测试时，我从我的服务器捕获了 SMTP 日志，如下所示（当然是经过清理的）：

SENT: 220 my.mailserv.er ESMTP
RECEIVED: EHLO CLIENTAPP
SENT: 250-my.mailserv.er[nl]250-SIZE 25600000[nl]250 AUTH LOGIN
RECEIVED: AUTH login bWFpbHRlc3RAbXkubWFpbHNlcnYuZXI=
SENT: 334 UGFzc3dvcmQ6
RECEIVED: ***
SENT: 235 authenticated.
RECEIVED: MAIL FROM:<mailtest@mailserv.er>
SENT: 250 OK
RECEIVED: RCPT TO:<happyuser@mailserv.er>
SENT: 250 OK
RECEIVED: DATA
SENT: 354 OK, send.

我的服务器需要 SMTP AUTH，您可以看到，在我的客户端发送 AUTH 命令后，服务器响应状态代码 334，以及Password:. 因此，我建议打开SmtpClient 的跟踪功能，以便您可以看到这两种情况下发生的情况。

我正在运行 LINQPad 4.31，我的 linqpad.config 文件包含：

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <system.net>
    <mailSettings>
      <smtp from="mailtest@mailserv.er">
        <network host="my.mailserv.er" port="25" userName="mailtest@mailserv.er" password="supersecure"/>
      </smtp>
    </mailSettings>
  </system.net>
</configuration>

LINQPad 查询如下：

SmtpClient mailer = new SmtpClient();

Guid g = Guid.NewGuid();
g.Dump("Message GUID");

MailMessage msg = new MailMessage();
msg.Subject = "Test:" + g;
msg.To.Add(new MailAddress("happyuser@mailserv.er"));
msg.Body = "I HAS A BODY";
mailer.Send(msg);