问题描述
为什么示例不起作用？即使 SMTP server 也可以。
我设置 Outlook 只是为了测试 SMTP 服务器。一切都好。我可以发送和接收邮件。
问题在于 C# 代码。它总是返回超时异常。即使我将超时设置为最大整数。
SMTP 服务器端口正常，因为使用 Outlook 客户端没有任何问题。只需检查顶部的链接即可查看 SMT 服务器的配置。相同的选项来自相同的网络。
public void SendAbvBg(string message)
{
var Smtp = new SmtpClient("smtp.abv.bg",465);
Smtp.UseDefaultCredentials = false;
Smtp.EnableSsl = true;
Smtp.Timeout = 80000;
Smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
Smtp.Credentials = new System.Net.NetworkCredential("mail@abv.bg","pass");
MailMessage msg = new MailMessage();
msg.Body = message;
msg.From = new MailAddress("mail@abv.bg","name");
msg.To.Add("mail@abv.bg");
msg.HeadersEncoding = Encoding.UTF8;
msg.BodyEncoding = Encoding.UTF8;
msg.IsBodyHtml = true;
msg.Subject = "Form";
msg.SubjectEncoding = Encoding.UTF8;
msg.Headers.Add("MIME-Version","1.0");
msg.Headers.Add("Content-Language","en-us");
try
{
Smtp.Send(message);
}
catch(Exception e)
{
// timeout exception
}
}
这怎么可能？标准 Outlook pop/smtp 工作。代码 - 不！为什么？ 除此之外，Outlook 配置超时为 2 分钟。
我已经尝试了 5 分钟 Timeout = 300000 并且仍然收到错误消息：
Message = "操作超时。"
SMT 服务器归 ABV.BG 所有。它是一个非常古老的 UNIX smtp 服务器。 客户端代码和 Outlook 客户端在同一个办公公司网络中。网络不限制任何端口或策略。 Outlook 使用与代码示例相同的配置和选项完美运行。这证明问题与网络、防火墙或任何其他限制无关。这是代码中的错误。
会不会是默认 TargetName = "SMTPSVC/smtp.abv.bg" 的问题？ https://docs.microsoft.com/en-us/dotnet/api/system.net.mail.smtpclient.targetname?view=net-5.0
GMAIL 没问题，它不是当前主题的一部分。
https://passport.abv.bg/app/profiles/sendtosupport/form?from=abv.bg
来自 https://www.smtper.net/ 的测试
解决方法
我已经创建了一个类来测试 SMTP 访问。简单测试使用您的数据调用 SmtpSeverProbe(...) 方法。成功后您将收到电子邮件。将测试正常端口 25,465,587 将测试 SSL。
using System;
using System.IO;
using System.Net;
using System.Net.Security;
using System.Net.Sockets;
using System.Text;
namespace CommonCore.Tests
{
// Based in:
// https://gist.github.com/xamlmonkey/4737291
//Normal port 25 text,465 SSL,587 text then STARTSSL
/// <summary>
/// For Testing access to SMTP server.
/// </summary>
public static class SmtpTests
{
static int connectionTimeout = 1300;
/// <summary>
/// Tests RELAY,Try to send email port 25 with and without StartSSl,port 465 with SSL,Port 587 with StartSSL.
/// Returns a resume Log,but you have a 'out string log' variable with details.
/// </summary>
/// <param name="login"></param>
/// <param name="password"></param>
/// <param name="server">To test SSL use a name that exists in the Server Certificate,For SSL avoid a IP</param>
/// <param name="to">Accepts all formats: ...@... or "......." <....@....></param>
/// <param name="msg">Message in the body</param>
/// <param name="log">very detailed Log</param>
/// <param name="error">Only Errors Log</param>
/// <param name="from"></param>
/// <returns></returns>
public static string SmtpServerProbe(string login,string password,string server,string to,string msg,out string log,out string error,string from = null)
{
//Normal port 25 text,587 text then STARTSSL
string resume = "";
error = "";
log = Environment.NewLine;
string _resume = "";
string _error = "";
int port;
bool forceSsl;
from = from ?? "\"Test Email\" <test@email.com>";
bool _sendok = false;
System.Net.Mail.MailAddress addr = null;
try
{
addr = new System.Net.Mail.MailAddress(from);
}
catch
{
error = "'from' email address is incorrect.";
log += "!! Error : " + error;
resume = Environment.NewLine + $"[FAIL] 'from' incorrect format > '{from}'" + Environment.NewLine;
return resume;
}
try
{
addr = new System.Net.Mail.MailAddress(to);
}
catch
{
error = "'to' email address is incorrect.";
log += "!! Error : " + error;
resume = Environment.NewLine + $"[FAIL] 'to' incorrect format > '{to}'" + Environment.NewLine;
return resume;
}
//Test Relay
port = 25;
forceSsl = false;
log += "----------------------------------" + Environment.NewLine +
"Testing RELAY." + Environment.NewLine +
"(user is not authenticated,email is sento to 'test@gmail.com')" + Environment.NewLine;
_sendok = Tests.SmtpTests.ScanSMTP("","",server,port,forceSsl,"\"Test Email\" <test@email.com>","test@gmail.com","Relay Test",out string _log,out _resume,out _error);
if (_sendok)
{
resume += "SERVER IS ACCEPTING RELAY THAT'S VERY BAD IDEIA";
resume += Environment.NewLine + $" (maybe it has an exception to this Host or IP '{System.Net.Dns.GetHostName()}')";
log += _log + Environment.NewLine;
log += "----------------------------------" + Environment.NewLine + " SERVER IS ACCEPTING RELAY THAT'S VERY BAD IDEIA" + Environment.NewLine + Environment.NewLine;
}
else
{
log += "----------------------------------" + Environment.NewLine + " SERVER is not accepting Relay,that's good." + Environment.NewLine + Environment.NewLine;
}
//TEST SMTPS
port = 465;
forceSsl = true;
log += Environment.NewLine + "__________________________________" + Environment.NewLine +
$"Testing port {port} / force SSL={forceSsl}";
_sendok = Tests.SmtpTests.ScanSMTP(login,password,from,to,msg,out _log,out _error);
log += _log;
error += Environment.NewLine + _error;
resume += _resume;
//TEST SMTP with STARTSSL
port = 25;
forceSsl = false;
log += Environment.NewLine + "__________________________________" + Environment.NewLine +
$"Testing port {port} / try STARTSSL=true";
_sendok = Tests.SmtpTests.ScanSMTP(login,out _error);
log += _log;
error += Environment.NewLine + _error;
resume += _resume;
//TEST SMTP no STARTSSL
port = 25;
forceSsl = false;
log += Environment.NewLine + "__________________________________" + Environment.NewLine +
$"Testing port {port} / try STARTSSL=false";
_sendok = Tests.SmtpTests.ScanSMTP(login,out _error,true,false);
log += _log;
error += Environment.NewLine + _error;
resume += _resume;
//Test port 587 with STARTSSL
port = 587;
forceSsl = false;
log += Environment.NewLine + "__________________________________" + Environment.NewLine +
$"Testing port {port} / try STARTSSL=true";
_sendok = Tests.SmtpTests.ScanSMTP(login,out _error);
log += _log;
error += Environment.NewLine + _error;
resume += _resume;
return resume;
}
/// <summary>
/// Tests the SMTP server and try to send a test Email
/// </summary>
/// <param name="login"></param>
/// <param name="password"></param>
/// <param name="server">Server DNS name</param>
/// <param name="port"></param>
/// <param name="forceSsl"></param>
/// <param name="from"></param>
/// <param name="to"></param>
/// <param name="msg">Message to send to the body</param>
/// <param name="log">Detailed Log</param>
/// <param name="resume">Resumed Log</param>
/// <param name="error">Erro Log</param>
/// <param name="checkcertificate">Check if SSL Certificate in the Server is acceptable</param>
/// <param name="trystartssl">try to send the command STARTTLS</param>
/// <returns></returns>
public static bool ScanSMTP(string login,int port,bool forceSsl,string from,out string resume,bool checkcertificate = true,bool trystartssl = true)
{
#region check parameters
log = Environment.NewLine;
error = "";
resume = "";
string _fromaddrstr = "";
string _toaddrstr = "";
string _errorResume = $"[FAIL] Port={port},Force SSL={forceSsl},try STARTSSL={trystartssl}";
System.Net.Mail.MailAddress addr = null;
if (!String.IsNullOrEmpty(login))
{
if (String.IsNullOrEmpty(password))
{
error = "If login is not empty than the password cannot be empty";
log += "!! Error : " + error;
resume = Environment.NewLine + $"[FAIL] 'password' is missing" + Environment.NewLine;
return false;
}
}
try
{
addr = new System.Net.Mail.MailAddress(from);
_fromaddrstr = addr.Address;
}
catch
{
error = "'from' email address is incorrect.";
log += "!! Error : " + error;
resume = Environment.NewLine + $"[FAIL] 'from' incorrect format > '{from}'" + Environment.NewLine;
return false;
}
try
{
addr = new System.Net.Mail.MailAddress(to);
_toaddrstr = addr.Address;
}
catch
{
error = "'to' email address is incorrect.";
log += "!! Error : " + error;
resume = Environment.NewLine + $"[FAIL] 'to' incorrect format > '{to}'" + Environment.NewLine;
return false;
}
#endregion
try
{
#region support variables
string _response = "";
string _msgfotter = "";
StreamReader clearTextReader = null;
StreamWriter clearTextWriter = null;
StreamReader sslreader = null;
StreamWriter sslwriter = null;
SslStream sslStream = null;
// Depending on checkcertificate value stream may ignore Certificate Errors
// like: Hostname not in the certificate and Certificate Chain Errors
SslStream GetSslStream(Stream innerstream)
{
if (checkcertificate)
return new SslStream(innerstream);
else
return new SslStream(
innerstream,false,new RemoteCertificateValidationCallback((s,c,h,e) => true),null
);
}
#endregion
#region support internal methods
void ExitError(string str,ref string _log,ref string _error)
{
_error = str;
_log += "!! Error : " + str + Environment.NewLine + Environment.NewLine;
if (sslStream == null)
{
clearTextWriter.WriteLine("QUIT");
}
else
{
sslwriter.WriteLine("QUIT");
}
}
string AskReceive(string commandline,ref string _log)
{
if (sslStream == null)
{
_log += "> " + commandline + Environment.NewLine;
clearTextWriter.WriteLine(commandline);
string _str;
System.Threading.Thread.Sleep(200);
//while (!clearTextReader.EndOfStream)
//while (!String.IsNullOrEmpty(_str))
// {
// System.Threading.Thread.Sleep(200);
// //yield return _str;
// _str = clearTextReader.ReadLine();
// _log += "< " + _str + Environment.NewLine;
//}
_str = clearTextReader.ReadLine();
_log += "< " + _str + Environment.NewLine;
return _str;
}
else
{
_log += "> " + commandline + Environment.NewLine;
sslwriter.WriteLine(commandline);
System.Threading.Thread.Sleep(200);
string _str = sslreader.ReadLine();
_log += "< " + _str + Environment.NewLine;
return _str;
}
}
bool Login(ref string _log,ref string _error)
{
if (!(_response = AskReceive($"AUTH LOGIN",ref _log)).StartsWith("334"))
{
ExitError(_response,ref _log,ref _error);
return false;
}
if (!(_response = AskReceive(Convert.ToBase64String(Encoding.UTF8.GetBytes($"{login}")),ref _error);
return false;
}
if (!(_response = AskReceive(Convert.ToBase64String(Encoding.UTF8.GetBytes($"{password}")),ref _log)).StartsWith("235"))
{
ExitError(_response,ref _error);
return false;
}
return true;
}
bool SendMsg(ref string _log,ref string _error)
{
// HELO JakesDominoApp
// MAIL FROM: jake@jakehowlett.com
// RCPT To: jhowlett@EITS
// DATA
// From: My Self <me@you.com>
// To: A secret list <you@me.com>
// Subject: A simple test
// Mime-Version: 1.0;
// Content-Type: text/html; charset="ISO-8859-1";
// Content-Transfer-Encoding: 7bit;
//
// <html>
// <body>
// <h2>An important link to look at!</h2>
// Here's an <a href="http://www.codestore.net">important link</a>
// </body>
// </html>
// .
// QUIT
if (!String.IsNullOrEmpty(login))
if (!Login(ref _log,ref _error))
return false;
if (!(_response = AskReceive($"MAIL FROM: <{_fromaddrstr}>",ref _log)).StartsWith("250"))
{
ExitError(_response,ref _error);
return false;
}
if (!(_response = AskReceive($"RCPT TO: <{_toaddrstr}>",ref _error);
return false;
}
string _return = AskReceive($"DATA",ref _log);
if (_return.Substring(0,1) == "5")
{
ExitError(_return,ref _log);
return false;
}
string _details = $"Server:'{server}' | Login:'{login}' | port:{port} | try STARTTSL:{trystartssl} | Force SSL:{forceSsl}";
if (!AskReceive(
$"From: {from}" + Environment.NewLine +
$"To: {to}" + Environment.NewLine +
$"Subject: " + _details +
Environment.NewLine + Environment.NewLine +
msg + Environment.NewLine + Environment.NewLine +
"__________________________________________________" + Environment.NewLine + Environment.NewLine +
_details + " " + _msgfotter + Environment.NewLine +
Environment.NewLine + Environment.NewLine + ".",ref _log).StartsWith("250"))
{
ExitError(_response,ref _error);
return false;
}
AskReceive($"QUIT",ref _log);
return true;
}
#endregion
#region method body
TcpClient client = new TcpClient();
//Make the connection with timeout
if (!client.ConnectAsync(server,port).Wait(connectionTimeout))
{
//log = ex.ExceptionToString();
error = $"Could not connect '{server}' at port '{port}'";
log += Environment.NewLine + error + Environment.NewLine;
resume = Environment.NewLine + $"[FAIL] Port={port}. Could not connect '{server}' at port '{port}'" + Environment.NewLine;
return false;
}
using (client)
{
if (forceSsl)
{
using (NetworkStream stream = client.GetStream())
using (sslStream = GetSslStream(stream)) // new SslStream(stream))
{
sslStream.AuthenticateAsClient(server);
using (sslreader = new StreamReader(sslStream))
using (sslwriter = new StreamWriter(sslStream) { AutoFlush = true })
{
log += Environment.NewLine + Environment.NewLine + "## SSL connection (safe)" + Environment.NewLine;
string connectResponse = sslreader.ReadLine();
log += "< " + connectResponse + Environment.NewLine;
if (!connectResponse.StartsWith("220"))
{
ExitError(_response,ref log,ref error);
resume = Environment.NewLine + $"[FAIL] Port={port},Force SSL={forceSsl} (encrypted)";
return false;
}
if (!(_response = AskReceive($"HELO {Dns.GetHostName()}",ref log)).StartsWith("250"))
{
ExitError(_response,Force SSL={forceSsl} (encrypted)";
return false;
}
_msgfotter = $"Encrypted MSG using SMTP/S on port: {port}";
if (SendMsg(ref log,ref error))
{ resume = Environment.NewLine + $"[SUCCESS] Port={port},Force SSL={forceSsl} (encrypted)"; return true; }
else
{ resume = Environment.NewLine + $"[FAIL] Port={port},Force SSL={forceSsl} (encrypted)"; return false; }
}
}
}
else //Not SMTP/S (SSL)
{
using (NetworkStream stream = client.GetStream())
using (clearTextReader = new StreamReader(stream))
using (clearTextWriter = new StreamWriter(stream) { AutoFlush = true })
{
log += Environment.NewLine + Environment.NewLine + "## Plain text connection (UNSAFE)" + Environment.NewLine;
string connectResponse = clearTextReader.ReadLine();
log += "< " + connectResponse + Environment.NewLine;
if (!connectResponse.StartsWith("220"))
{
ExitError(connectResponse,ref error);
resume = Environment.NewLine + $"[FAIL] Port={port},Force SSL={forceSsl} (unsafe,plain text)";
return false;
}
if (!(_response = AskReceive($"HELO {Dns.GetHostName()}",ref log)).StartsWith("250"))
{
ExitError(_response,plain text)";
return false;
}
if (trystartssl)
{
if ((_response = AskReceive("STARTTLS",ref log)).StartsWith("220"))
{
clearTextReader = null;
clearTextWriter = null;
using (sslStream = GetSslStream(stream)) // new SslStream(stream))
{
//TLS Start
sslStream.AuthenticateAsClient(server);
log += Environment.NewLine + Environment.NewLine + "## TLS connection (safe)" + Environment.NewLine;
using (sslreader = new StreamReader(sslStream))
using (sslwriter = new StreamWriter(sslStream) { AutoFlush = true })
{
if (!AskReceive($"HELO {Dns.GetHostName()}",ref log).StartsWith("250"))
{ ExitError(_response,ref error); resume = $"[FAIL] Port={port},Force SSL={forceSsl} (encrypted)"; return false; }
_msgfotter = "Encrypted MSG using STARTSSL on port: " + port.ToString();
if (SendMsg(ref log,ref error))
{
resume = Environment.NewLine +
$"[SUCCESS] Port={port},try STARTSSL={trystartssl} (encrypted)";
return true;
}
else
{
resume = Environment.NewLine +
$"[FAIL] Port={port},try STARTSSL={trystartssl} (encrypted)";
return false;
}
}
}
}
}
if ((trystartssl && !_response.StartsWith("220")) || !trystartssl)
{
if (trystartssl)
log += "## Does not accept StartSSL" + Environment.NewLine;
_msgfotter = "Unsafe MSG using plain text on port: " + port.ToString();
if (SendMsg(ref log,ref error))
{
resume = Environment.NewLine +
$"[SUCCESS] Port={port},try STARTSSL={trystartssl} (unsafe,plain text)";
return true;
}
else
{
resume = Environment.NewLine +
$"[FAIL] Port={port},plain text)";
return false;
}
}
return false;
}
}
}
#endregion
}
catch (Exception ex)
{
if (ex.Message == @"The remote certificate is invalid according to the validation procedure.")
{
log += $"The host name '{server}' must exist in the server SSL certificate. Don't use IP or host names not in the Certificate" + Environment.NewLine;
}
error = ex.Message;
log += "!! Error : " + ex.Message + Environment.NewLine;
resume += Environment.NewLine + _errorResume;
return false;
}
}
}
}