Unable to send email inside my console application. error “No connection could be made because the target machine actively refused it”

Question

I have the following console application, which connect to our SharePoint online site collection and send emails:-

using (ClientContext context = new ClientContext(scurl))
            {
                SecureString passWord = new SecureString();
                foreach (var cc in s)
                passWord.AppendChar(cc);
                context.Credentials = new SharePointOnlineCredentials("admin@****.onmicrosoft.com", passWord);

                List oList = context.Web.Lists.GetByTitle(listname);
                CamlQuery camlQuery = new CamlQuery();
                camlQuery.ViewXml = "<View><Query><Where><And><Eq><FieldRef Name='Contract_x0020_Review_x0020_Date'/>" +
                    "<Value Type='DateTime'><Today /></Value></Eq><Eq><FieldRef Name='Contract_x0020_Status'/><Value Type='String'>Active</Value></Eq></AND></Where></Query><RowLimit>5000</RowLimit></View>";
                ListItemCollection collListItem = oList.GetItems(camlQuery);

                context.Load(collListItem,
items => items.Include(
item => item["Contract_x0020_Status"],
item => item["Person_x0020_Responsible"],
item => item["Title"],
item => item["Id"]

));

                context.ExecuteQuery();
                foreach (ListItem oListItem in collListItem)
                {



                    oListItem["Contract_x0020_Status"] = "Needs Review";
                    oListItem.Update();
                    context.ExecuteQuery();
                    var userValue = (FieldUserValue)oListItem["Person_x0020_Responsible"];
                    var user = context.Web.GetUserById(userValue.LookupId);
                    context.Load(user, x => x.Email);
                    context.Load(user, x => x.Title);
                    context.ExecuteQuery();

                    //item.RoleAssignments.RemoveById(spgroup.ID);

                    MailMessage mail = new MailMessage("no-reply@sharepointonline.com", user.Email);
                    SmtpClient client = new SmtpClient();
                    client.Port = 587;
                    client.DeliveryMethod = SmtpDeliveryMethod.Network;
                    client.UseDefaultCredentials = false;
                    client.EnableSsl = true;
                    client.Host = "smtp.office365.com";
                    mail.Subject = "The Contract has revowed";
                    //mail.To = user.Email[0];
                    mail.Bcc.Add(ConfigurationManager.AppSettings["bccemail"].ToString());
                    mail.Body = "Hi <span><b>" + user.Title + "</b></span><br/>The Review Date for the following Contract has been reached <a href='https://***.sharepoint.com/sites/businessfunctions/operations/Lists/Supplier%20Contracts/DispForm.aspx?ID=" + oListItem.Id.ToString() + "'>" + oListItem["Title"]+ "</a><br><span style='color=Blue'>TDM Group Operations</span>";
                    client.Send(mail);



                }

                // Now update the list.
            }

but the client.Send(mail); will raise this exception:-

System.Net.Mail.SmtpException was unhandled
  HResult=-2146233088
  Message=Failure sending mail.
  Source=System
  StackTrace:
       at System.Net.Mail.SmtpClient.Send(MailMessage message)
       at ConsoleApplication1.Program.Main(String[] args) in c:\Users\***Program.cs:line 94
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException: System.Net.WebException
       HResult=-2146233079
       Message=Unable to connect to the remote server
       Source=System
       StackTrace:
            at System.Net.ServicePoint.GetConnection(PooledStream PooledStream, Object owner, Boolean async, IPAddress& address, Socket& abortSocket, Socket& abortSocket6)
            at System.Net.PooledStream.Activate(Object owningObject, Boolean async, GeneralAsyncDelegate asyncCallback)
            at System.Net.ConnectionPool.GetConnection(Object owningObject, GeneralAsyncDelegate asyncCallback, Int32 creationTimeout)
            at System.Net.Mail.SmtpConnection.GetConnection(ServicePoint servicePoint)
            at System.Net.Mail.SmtpClient.GetConnection()
            at System.Net.Mail.SmtpClient.Send(MailMessage message)
       InnerException: System.Net.Sockets.SocketException
            HResult=-2147467259
            Message=No connection could be made because the target machine actively refused it 52.97.133.226:587
            Source=System
            ErrorCode=10061
            NativeErrorCode=10061
            StackTrace:
                 at System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress)
                 at System.Net.ServicePoint.ConnectSocketInternal(Boolean connectFailure, Socket s4, Socket s6, Socket& socket, IPAddress& address, ConnectSocketState state, IAsyncResult asyncResult, Exception& exception)
            InnerException: 

so can anyone advice on this?

Answer 1

This isn't a SharePoint Online question (and I suspect your message will be rejected if you're also attempting to use a domain other than your own) but rather an Exchange Online question.

However, you can review the documentation for using Office 365 SMTP relay.

How to set up a multifunction device or application to send email using Office 365