Failed to send e-mail message ... temporary failure

[JustinDallas]

Hello Folks,

I'm working with my NPrinting system, and when I go to the "Run now" button, nothing happens, yet I see this in the error logs.

Qlik.NPrinting.Repo 17.6.0.0 Qlik.NPrinting.Repo.Service.MailService 20180322T165336.181-04:00
ERROR QLIKSENSE Nprinting Task Identity 0 0 0 0 0 0 0 0
Failed to send e-mail message to [redacted]@[redacted].net. 
ERROR: 4.1.0 ... temporary failure. 
Stack trace:    at MailKit.Net.Smtp.SmtpClient.ProcessMailFromResponse(MimeMessage message, MailboxAddress mailbox, SmtpResponse response)↓↓   
at MailKit.Net.Smtp.SmtpClient.MailFrom(FormatOptions options, MimeMessage message, MailboxAddress mailbox, SmtpExtension extensions, CancellationToken cancellationToken)↓↓   
at MailKit.Net.Smtp.SmtpClient.Send(FormatOptions options, MimeMessage message, MailboxAddress sender, IList`1 recipients, CancellationToken cancellationToken, ITransferProgress progress)↓↓   
at MailKit.Net.Smtp.SmtpClient.Send(FormatOptions options, MimeMessage message, CancellationToken cancellationToken, ITransferProgress progress)↓↓   
at MailKit.MailTransport.Send(MimeMessage message, CancellationToken cancellationToken, ITransferProgress progress)↓↓   
at MailKit.MailTransport.<>c__DisplayClass2_0.<SendAsync>b__0()↓↓   
at System.Threading.Tasks.Task.Execute()↓↓--- End of stack trace from previous location where exception was thrown ---↓↓   
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()↓↓   
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)↓↓   
at Qlik.NPrinting.Repo.Service.MailService.<SendEmailAsync>d__4.MoveNext() in c:\Jws\workspace\NP-REL-17.6.0.0-BR-01-build\server\NPrinting\src\Repo\Service\MailService.cs:line 106.

While it says the error is temporary, this NPrinting system has been emailing folks all-day.  I can also send test emails from my Outlook and have a co-worker receive them so I know it's not the SMTP server being down completely.

Any help is greatly appreciated.

[Lech_Miszkiewicz · Accepted solution]

Hi Justin,

Install SMTP4DEV dummy server CodePlex Archive and use it as SMTP server for your NPrinitng. If NPrinitng creates and sends all emails without issues to this dummy ("smtp4dev") SMTP server you will know for sure that your actual SMTP server might have some policies which prevent your NPrinting from sending too many emails. This might be basicly  anti-spam SMTP server policy.

cheers

Lech

[JustinDallas]

It's working today, but I'll let you know if there are any other problems.  Thanks for hipping me to that SMTP debug, helps me cut down on guesswork of where the error might be.