Here is my code:
SmtpClient client = new SmtpClient();
client.UseDefaultCredentials = true;
using (client as IDisposable)
{
foreach (MailAddress addr in Addresses)
{
if (addr != null)
{
try
{
message.To.Clear();
message.To.Add(addr);
client.Send(message);
}
catch (Exception ex)
{
Log(ex);
}
i++;
}
}
}
every 100 seconds, I log a message saying
The operation has timed out.
Is this a client side setting or on the actual mail server?
The problem happens when you are not able to connect to SMTP server and thats why this timeout message occur. So this message occurs on your client when your client is not able to connect to your SMTP Server:
100 second is default value as described below:
http://msdn.microsoft.com/en-us/library/system.net.mail.smtpclient.timeout.aspx
There could be several issue why this prblem could occur i.e. Wrong SMTP address, SMTP reject, Port setting, SSL configuration etc which you need to fix.
I was also expeiencing this timeout. The problem seemed to be that the email I was trying to send out had a single email address but repeated 30+ times (this was a dev environment where the real recipient email addresses were change to a dev one). Cutting this number (to about 20) resolved the issue. Obviously, this is an issue specific to my own SMTP server, but the recipient list is something to look at if all else fails.
Related
I am sending approximately 5000 emails to IIS smtp server Windows 2012 R2 (Server1) using aspose email client (using c#) in a loop. The emails fired queue up in smtp server queue. From that queue, they are all sent to the same destination (an oracle email filing server - Server2).
The problem is - approx 700-800 (randomly every time) emails are getting lost in transit.
Questions -
Is there any way that i can queue all the emails received on Server1 to ensure that it is receiving complete 5000 emails? Any setting, so it can receive emails but do not forward them?
Is smtp email delivery not guaranteed to the recipient? Since there is no throttling mechanism, i think i am choking the network by sending large number of emails, and then emails in lost in network. If it is so, is there a mechanism by which smtp server can be configured to process queue slowly. Send out a few and then wait and so on.
Aspose.Email also let you send the email in the form of bulks as well. Moreover, it is also dependent on server side that how much bulk email it may handle at any given time so as to avoid any bombardment of emails as well. There may be settings on server side. However, from Aspose.Email perspective, you may please consider using following sample code rather than sending via loops. You can divide big chunks of emails into small bulks and then send via Bulk email sending option provided by Aspose.Email.
SmtpClient client = new SmtpClient("mail.server.com", 25, "Username", "Password");
//Create instances of MailMessage class and Specify To, From, Subject and Message
MailMessage message1 = new MailMessage("msg1#from.com", "msg1#to.com", "Subject1", "message1, how are you?");
MailMessage message2 = new MailMessage("msg1#from.com", "msg2#to.com", "Subject2", "message2, how are you?");
MailMessage message3 = new MailMessage("msg1#from.com", "msg3#to.com", "Subject3", "message3, how are you?");
//Create an instance of MailMessageCollection class
MailMessageCollection manyMsg = new MailMessageCollection();
manyMsg.Add(message1);
manyMsg.Add(message2);
manyMsg.Add(message3);
//Use client.BulkSend function to complete the bulk send task
try
{
// Send Message using BulkSend method
client.Send(manyMsg);
Console.WriteLine("Message sent");
}
catch (Exception ex)
{
Trace.WriteLine(ex.ToString());
}
I'm trying to send a mail message using System.Net.Mail.SmtpClient with SSL enabled. While changing no external factors (i.e. hit F5, then hit F5 Again - or even in a loop) it works some times, but most of the times it fails.
Example code:
public void SendMail()
{
using (var client = new SmtpClient())
{
MailMessage mailMessage = new MailMessage();
client.EnableSsl = true;
client.Host = "smtp.example.com";
client.Timeout = 10000;
client.DeliveryMethod = SmtpDeliveryMethod.Network;
mailMessage.From = new MailAddress("from#example.com");
mailMessage.To.Add(new MailAddress("to#example.com"));
mailMessage.Subject = "Test";
mailMessage.Body = "Message " + DateTime.Now.ToString();
try
{
client.Send(mailMessage);
}
catch (Exception ex)
{
// This being a Pokemon block is besides the point
}
}
}
In my catch block I just get a timeout, but if I set up a trace for System.Net and System.Net.Sockets I can see a number of different exceptions:
Unable to read data from the transport connection: A blocking operation was interrupted by a call to WSACancelBlockingCall
Unable to read data from the transport connection: An established connection was aborted by the software in your host machine
Cannot access a disposed object
Reading is not supported on this stream
Writing is not supported on this stream
All of which happen post EHLO, STARTTLS and authentication. The client and the server are chatting along in their cryptographic ways when the exceptions are thrown.
System.Net.Mail.SmtpClient.Send() is the the only frame all call stacks have in common.
Of course I've tried changing the code in a number of ways, such as setting client.UseDefaultCredentials, using client.SendAsync() and whatnot. But I suspect it's something entirely different knocking the connection over at different times - a configuration error on one of the machines involved perhaps?
So I've checked the Event Logs for signs of something messing with the connection, but I haven't found anything.
Any suggestions as to what I should be looking for here?
Sometimes a timeout is just a timeout ...
Digging further into this issue I used Wireshark to see what was going on at the network level.
When the failures happened, the client machine invariably sent a TCP [RST, ACK] packet around 10 seconds after EHLO. A timespan conspicuously close to my timeout value. When I doubled the timeout value the mails came through without failure every single time.
Of course if we were to spend more than 10 seconds sending each mail, we'd soon be queuing up mails for hours in our production system, so I needed to find out why it took so long.
One detail caught my attention:
The client was spending upwards of four seconds between two packets. And it was generally spending hundreds of milliseconds between packets whereas the server would respond within tens.
The next step was to build the code without debug symbols and measure again without a debugger attached. The time spent per e-mail sent immediately went sub-second. Now it's no news to me that code runs slower with a debugger attached, but seeing it run that much slower was a surprise.
So the lessons for me to learn were: Try not to overanalyze, and when timing is involved kill the debugger once in a while.
This should be a comment (I don't have reputation to make comments), but it could be a firewall issue, given you're getting an "Unable to read data from the transport connection: An established connection was aborted by the software in your host machine" error (basically, firewall or anti-virus cancelled your attempt to send a mail).
The error "Unable to read data from the transport connection: A blocking operation was interrupted by a call to WSACancelBlockingCall" happens when a stream is closed - see this question - and the other errors you've listed seem like they're related to trying to access a stream when it's closed, too.
All these error point to a common cause, a connection cancelled somewhere between you and the server and most likely on your machine/ network, and you get different errors depending at what point the effect propagates through to your application.
Another thing is, if you use
Credentials = new NetworkCredential(fromAddress.Address, fromPassword)
then you have to enable ssl afterwards, not before, otherwise it's cleared.
I suppose you have missed to set Credentials property of your host. However the another reason for exceptions may be wrong host name and port.Try something like :
public void SendMail()
{
try
{
var fromAddress = new MailAddress("from#example.com", "Some text");
var toAddress = new MailAddress("to#example.com");
const string fromPassword = "from account password";
var smtp = new SmtpClient
{
Host = "smtp.example.com",
Port = "your host port", //for gmail is 587
EnableSsl = true,
DeliveryMethod = SmtpDeliveryMethod.Network,
UseDefaultCredentials = false,
Credentials = new NetworkCredential(fromAddress.Address, fromPassword)
};
using (var message = new MailMessage(fromAddress, toAddress)
{
Subject = "Test",
Body = "Message " + DateTime.Now.ToString()
})
{
smtp.Send(message);
}
}
catch (Exception ex)
{
//do something
}
}
It is tested with gmail host which is smtp.gmail.com and it works correctly
I am trying to create socket and connect to a device. The problem occurs when the device is not in the network and I try to connect. I get false as response (which is ok and on which base I update status of my device), but the problem is that I get the response in 21 seconds. I am using this function to connect:
public bool Connect(IPEndPoint ipEndPoint, IPAddress ipAddress, Guid id, bool isAlive)
{
try
{
clSocket = new Socket(ipAddress.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
clSocket.NoDelay = false;
clSocket.ReceiveTimeout = 1000;
clSocket.SendTimeout = 1000;
clSocket.Connect(ipEndPoint);
return true;
}
catch (Exception ex)
{
return false;
}
}
As much as I read about "21 seconds timeout" I found out that I have to change the register:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters
Value Name: TcpMaxDataRetransmissions
Data Type: REG_DWORD - Number
Valid Range: 0 - 0xFFFFFFFF
Default: 3
I am reffering to this articles:
http://getin2me.blogspot.com/2010/08/are-you-also-facing-windows-sockets-21.html and this post:
https://social.msdn.microsoft.com/Forums/en-US/fd586377-34b3-4cb8-a3af-0a24c608e399/connectex-winsock-question?forum=vcgeneral
Why in Windows 8 I can not find this register? Is there any other solution so I can get quick (by quick I mean normal <1ms to <20ms i.e.) response true(connected) or false(not connected)?
by quick I mean normal <1ms to <20ms i.e.)
If the device is not there you can not get a response about the failed connection that fast. A TCP connections gets established by the 3-way-handshake. In this handshake the client first sends a SYN packet to the server and waits for the SYN+ACK back.
If the server is there but the port is closed it will send a RST back (instead of SYN+ACK) and the client knows that that the server is unreachable. This can be done in RTT time, which is a few ms in a local network but can be easily more than 20ms if you are on the internet.
If the server is not there it can not send a response back. In this case the client will retry to send the SYN multiple times because the packet might simply be lost. How long it will wait for the response depends on the OS and tuning, but often the first retry is done after 1 second, the second after 3 seconds... until after some time the client simply gives up and assumes the server is not there. This means in this case it will take multiple seconds and there is nothing you can do about it.
You could try pinging the address first and see if you get a response, if you dont, dont attempt to try to connect to it
Ping pinger = new Ping();
try
{
PingReply reply = pinger.Send(ip);
if (reply.Status == IPStatus.Success)
{
}
else
{
}
}
I have a windows service which is scheduled to run below method every 5minutes and read emails and process the attachement i.e. convert tiff to pdf and update the database by reading the QR code of attachement, I have observed a issue recently the Service got hanged i.e. I could not stop it from services.msc and have to kill it from task manager although it worked well for last 2months without issue.
Upon investigating the log I observed the log entry was "IMAP 4 Client Authentication Started"
and it never reached "IMAP 4 Client Authentication Done" although as it is schedule to call this method every 5minutes I could see the logs from there on call to the below method
"call to processEmail for user Dept1 "
"call to processEmail for user Dept2 "
son on........
private readonly object _myLock = new object();
public void start()
{
// all the belwo variable read from config file...
Log.WriteLog("call to processEmail for user " + username);
ProcessEmail(host, username, password, connPort);
Log.WriteLog("Service Completed reading for user " + username);
}
public void ProcessEmail(string host, string username, string password, int connPort)
{
Monitor.Enter(_myLock); //_myLock defined at class level
Log.WriteLog("IMAP 4 Client Authentication Started");
using (Imap4Client imap = new Imap4Client())
{
try
{
imap.ConnectSsl(host, connPort); // port 993 for SSL Connect
imap.Login(username, password);
imap.Command("capability");
Log.WriteLog("IMAP 4 Client Authentication Done");
//fllowed by reading email from Inbox and junk emails.
}
catch (Exception ex)
{
Log.WriteLog(ex.Message);
}
finally
{
Monitor.Exit(_myLock);
}
}
}
My concern is if due to some reason imap.Login(username, password) fails, why the code block holds the lock by not allowing other instances to login as in finally block I am releasing the lock Monitor.Exit(_myLock), and I don't even see the exception recorded in log file, does imap.Login(username, password) trying to connect for ever to login, any suggestion/help on this would be of great help.
Again - this issue occurred today and from the log I could see this time
Message: Unable to read data from the transport connection: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.
followed by -
Service Completed reading for user " + username
and then again sequentially...
**call to processEmail for user Dept1 **
**call to processEmail for user Dept2 **
Is this issue has something to do with Activeup.Net.Imap4 client or could itbe Deadlock issue as I don't see anything that would cause deadlock..
After looking into Imap4 I couldn't find much to do in connectssl,Login and command method as to why it's going unresponsive and causing deadlock I have plan to implement the below solution for the issue -
Log.WriteLog("IMAP 4 Client Authentication Started");
using (Imap4Client imap = new Imap4Client())
{
try
{
imap.ConnectSsl(host, connPort); // port 993 for SSL Connect
imap.Login(username, password);
imap.Command("capability");
Log.WriteLog("IMAP 4 Client Authentication Done");
//fllowed by reading email from Inbox and junk emails.
try
{
Monitor.Enter(_myLock);
ReadEmails(imap, "inbox");
LogHelper.WriteLogEntry("Retrieving junk e-mail unread emails started");
ReadEmails(imap, "junk");
}catch(Exception ex)
{
Log.WriteLog(ex.Message);
}
finally
{
Monitor.Exit(_myLock);
}
}
catch (Exception ex)
{
Log.WriteLog(ex.Message);
}
}
Please advice if any better solution.
I can't seem to find the cause for this problem.
Sometimes I get SmtpException "4.7.0 timeout waiting for client input" being thrown on using the following c# code for .net-4.0:
using System;
using System.Net.Mail;
namespace SendMail
{
class Program
{
static void Main(string[] args)
{
for (int i = 0; i < 100; i++)
{
string html = "<h1>TEST</h1>";
using (MailMessage mail = new MailMessage("sender#domain.com", "receiver#domain.com"))
{
mail.Subject = "Test";
mail.IsBodyHtml = true;
mail.Body = html;
using (SmtpClient client = new SmtpClient("<internal ip address>"))
{
client.UseDefaultCredentials = false;
client.Credentials = new System.Net.NetworkCredential("<user name>", "<password>");
client.DeliveryMethod = SmtpDeliveryMethod.Network;
client.Send(mail);
}
}
}
}
}
}
It usually crashes at the second attempt (i == 1).
I am aware I should create a single SmtpClient instance and reuse it in the loop but for the purpose of demonstration and in order to be as close as possible to the real code it has to be this way. While the above isn't quite like my production code it does suffer from the same random problem. I figured that if I could solve the problem with this code then I'd know what to do with my actual code, given that it really is a coding issue to begin with. I'm suspecting an obscure server configuration issue but I'm out of ideas on what it could possibly be.
Odd thing: despite being a timeout issue, the exception is thrown very quickly; there's no delay that would suggest an actual timing out problem.
The mail server is MS exchange-server-2007 running on windows-server-2008 SP2. There's no additional SMTP settings specified in app.config file.
I tried to put the code in a Do...While loop that tries five times to send the email back after putting the thread to sleep for one second. Unfortunately that doesn't help: when it fails, it will also fail at the very next attempts.
I also tried using Thread.Sleep(<delay>) before every calls to client.Send(message) but it made no appearant difference.
Our network admin is adamant on the network running without any issues (no packet drops caused by bad MTU setting or anything like that). He backs this up with the fact that there's only my code that seems to have problems (and he's right) and that it does not only happen on a segment of the network (also right).
It's unlikely that the firewall would be causing this either, as every mail my app sends is using internal addresses.
Anybody has a clue here? It would be much appreciated.
UPDATE:
I seem to be able to reproduce the problem every time when using default credentials instead:
using (SmtpClient client = new SmtpClient("<internal ip address>"))
{
client.UseDefaultCredentials = true;
client.DeliveryMethod = SmtpDeliveryMethod.Network;
client.Send(mail);
}
UPDATE 2:
Nope. Not every time. Everything now works again (until next time).
I really can't put my finger on it.
UPDATE 3:
Interesting new development today: I attempted to create a new account inside MS Outlook with the same address I use with Exchange. Only this time instead of adding it as an MS Exchange address I tried setting it up as a POP3/SMTP account. Here is what happened upon testing the connection:
It's in french but look at the last line: it is the exact same error message I got with my code. This is a clear indication to me that the issue is not within my code.
Of course, this also means that this whole thread shouldn't be on SO. Still, I hope this extra test can help fellow developers out there who are struggling with a similar issue.
This definitely sounds like a server or network issue. Reference this serverfault post for instance: https://serverfault.com/questions/344684/exchange-2007-email-error-451-4-7-0-timeout-waiting-for-client-input
It could be a firewall problem if there is a firewall between your machine and the exchange server. A firewall blocks ports between ip addresses, it doesn't matter where the email is going at all. Firewalls are the bane of my programming existence, so definitely ask your net admin if there is a firewall between the servers and have him check if it is working.
It could also be something like a bad NIC (network card) on the server or even a bad cable. Yes, your network admin said the network is rock solid... but never trust network admins. ;)
It could also be a problem with YOUR network card, network settings or ethernet cable, actually.
Have you tried running this from different computers?
You can fire if off async like by changing your code as follows. You will need to check the AggregateException to see if something bad happened on any of the executing threads.
static void Main(string[] args)
{
for (int i = 0; i < 100; i++)
{
string html = "<h1>TEST</h1>";
Task.Factory.StartNew(() =>
{
using (MailMessage mail = new MailMessage("sender#domain.com", "receiver#domain.com"))
{
mail.Subject = "Test";
mail.IsBodyHtml = true;
mail.Body = html;
using (SmtpClient client = new SmtpClient("<internal ip address>"))
{
client.UseDefaultCredentials = false;
client.Credentials = new System.Net.NetworkCredential("<user name>", "<password>");
client.DeliveryMethod = SmtpDeliveryMethod.Network;
client.Send(mail);
}
}
}).ContinueWith(aex => {
if (aex.Exception != null)
{
//add some logic to deal with the exception
}
});
}
}
it is better to define SmtpClient before the loop, same problem happened with me and this solved it.
using System;
using System.Net.Mail;
namespace SendMail
{
class Program
{
SmtpClient client = new SmtpClient("<internal ip address>");
static void Main(string[] args)
{
client.UseDefaultCredentials = false;
client.Credentials = new System.Net.NetworkCredential("<user name>", "<password>");
//client.EnableSsl = true;
//client.Port = 25;
client.DeliveryMethod = SmtpDeliveryMethod.Network;
for (int i = 0; i < 100; i++)
{
string html = "<h1>TEST</h1>";
using (MailMessage mail = new MailMessage("sender#domain.com", "receiver#domain.com"))
{
mail.Subject = "Test";
mail.IsBodyHtml = true;
mail.Body = html;
client.Send(mail);
}
}
}
}
}
I'm fairly new to this messaging issue. I have currently been working on a messaging application and occasionally this exception is thrown into the system.
So far the answers I have picked up on the internet point out that this is an error in the email sender's authentication. Perhaps the limitation of daily submissions and the hourly send limit may inhibit SMTP server authentication of the email. Example, in case smtps.bol.com.br has a limit of 50 emails per hour, having to have a 60 minute interval to send a new batch of messages.
I have done my tests here and I do not have a conclusive answer, but I believe that maybe the way is this. If they find the definitive solution, do not forget to post.
Make sure the objects call .Dispose() in all cases.
I saw this problem on a highly active production system that sends 5000+ emails a day, but the problem would only happen to about 5% of the emails. The code sending the email was written before .Net 4.0, which introduced the Dispose() call to SmtpClient and MailMessage. I made a very simple change to make sure both objects were disposed and have not seen the problem again in 5 days.
That same code that does NOT call Dispose() runs on less active systems without any problems. My theory is there is some kind of cumulative resource leak if you fail to call Dispose() and it only causes this error under heavy load.
I was getting similar error couple of years back on Amazon Aws server. It seems my security company "AllCovered.com" had to do a exception to my server ip address to allow send smtp emails.
I do get this error if anytime a new server created is forgotten to be put in exception.