Sending Automated Emails asynchronously using a C# Windows Service

Posted on 2013-06-10
Last Modified: 2013-06-11
Hi Experts,

I've been following the linked tutorial which provides instruction on how to set up a service to send emails asynchronously using names, email-addresses & dates stored in a database.
I have built the solution and installed the service on my local machine, the only significant difference between my project and the authors is that I want to send my mail through our exchange server whereas the author has used a gmail account.

If We look at the main email Method (below) I am seeing the Message Sent SUCCESS message in the event log for the service and it has correctly picked up my email address and name from the database as 'CustomerEmail' and 'CustomerName', So I presume that I am 99% there, what I don't get is the actual physical email arrive in my Inbox.....can anyone suggest where I might begin troubleshooting?

Someone else seemed to have similar trouble following the tutorial and the author suggested an SMTP problem and to check ports and settings...however all that is set in the project itself is a sever name and credentials - in our case we use these credentials to send out batch html emails via a console app so I am fairly confident that these are correct.

I am wondering if the fact that I am using a Windows service to send the email is seen as a security threat by our exchange server or something...but I've never done this before so really haven't a clue...

private void ServiceEmailMethod()
            eventLogEmail.WriteEntry("In Sending Email Method");

            EmailComponent.GetEmailIdsFromDB getEmails = new EmailComponent.GetEmailIdsFromDB();
            getEmails.connectionString = ConfigurationManager.ConnectionStrings["CustomerDBConnectionString"].ConnectionString;
            getEmails.storedProcName = "GetBirthdayBuddiesEmails";
            System.Data.DataSet ds = getEmails.GetMailIds();

            EmailComponent.Email email = new EmailComponent.Email();

            email.fromEmail = "";
            email.fromName = "example Name";
            email.subject = "Birthday Wishes";
            email.smtpServer = "";
            email.smtpCredentials = new System.Net.NetworkCredential("", "example password");

            foreach (System.Data.DataRow dr in ds.Tables[0].Rows)
                email.messageBody = "<h4>Hello " + dr["CustomerName"].ToString() + "</h4><br/><h3>We Wish you a very Happy" +
                                    "Birthday  to You!!! Have a bash...</h3><br/><h4>Thank you.</h4>";

                bool result = email.SendEmailAsync(dr["CustomerEmail"].ToString(), dr["CustomerName"].ToString());

                if (result == true)
                    eventLogEmail.WriteEntry("Message Sent SUCCESS to - " + dr["CustomerEmail"].ToString() +
                                             " - " + dr["CustomerName"].ToString());
                    eventLogEmail.WriteEntry("Message Sent FAILED to - " + dr["CustomerEmail"].ToString() +
                                             " - " + dr["CustomerName"].ToString());


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Question by:forsters
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LVL 75

Expert Comment

by:käµfm³d 👽
ID: 39234838
I am wondering if the fact that I am using a Windows service to send the email is seen as a security threat by our exchange server or something
Exchange has no idea what application sent the mail--it's just data received on some port so far as Exchange is concerned. Do you have any antivirus running on the windows service machine? AVs will often block traffic on port 25 in order to prevent machines from being turned into spam bots.

Author Comment

ID: 39234906
Hi Kaufmed,

Many thanks for your comment, we have just tested this theory by sending a mail from the service machine via telnet, which we are able to do without error, presumably that means port 25 is not being blocked...?
LVL 75

Expert Comment

by:käµfm³d 👽
ID: 39234924
presumably that means port 25 is not being blocked...?
That should be the case.

Where did the class EmailComponent.Email come from? Did you write that in-house, or is it a 3rd party library?
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Author Comment

ID: 39234959
It's part of a class library that you have to build in PART I of the tutorial - you will see the instructions if you look about halfway down this link of the tutorial
LVL 75

Accepted Solution

käµfm³d   👽 earned 500 total points
ID: 39235144
Hmmm...  Perhaps it's my naiveté, but that code doesn't look like it will give you a meaningful indication as to whether or not the mail succeeded. In SendEmailAsync, the BeginInvoke call will return immediately (i.e. it will not block), so as long as nothing raised an exception prior to that line, then the SendEmailAsync should always return true. I would try modifying the SendEmail (since that's what SendEmailAsync itself calls) to add in some logging--see if there are any exceptions being raised.

Author Comment

ID: 39235280
I have isolated the problem to the class, it looks to me like the toEmail and toName are not actually being assigned, if I ignore the Email.cs from the class library and set my toEmail direct, then I seem to be in business.

Many thanks for your help, you narrowed down my search.

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