This article was created in response to a support issue logged with K2. The content may include typographical errors and may be revised at any time without notice This article is not considered official documentation for K2 software and is provided “as is” with no warranties.

Issue

When trying to send an email to users in a different domain it does not work. Sending emails to users in the same domain does work.

Symptoms

When trying to send an email to other domain users, the following error appears:

"61020207","2018-10-22 08:04:05","Error","MessageBus","61007","SendMessageException","MessageBusRuntime","61007 Permanent failure sending message [WORKFLOW FOLIO]: System.Net.Mail.SmtpFailedRecipientException: Mailbox unavailable. The server response was: 5.7.54 SMTP; Unable to relay recipient in non-accepted domain at System.Net.Mail.SmtpTransport.SendMail(MailAddress sender, MailAddressCollection recipients, String deliveryNotify, Boolean allowUnicode, SmtpFailedRecipientException& exception) at System.Net.Mail.SmtpClient.Send(MailMessage message) at SourceCode.Net.Mail.SmtpConnection.Send(MailMessage message) at SourceCode.MessageBus.Imap.SmtpDestination.Send(String title, MessageExtendedInformation extended, IEnumerable`1 attachments, MessageBodyReader[] messageBodies) at SourceCode.MessageBus.Server.MessageBusRuntime.SourceCode.MessageBus.IMessageDestination.Send(String title, MessageExtendedInformation extended, IEnumerable`1 attachments, MessageBodyReader[] messageBodies)"

Resolution

This issue is related to SMTP or Email configuration. We need to create a relay connector to allow external domains to receive emails.

Please see the following Microsoft and community articles regarding this issue:

1. https://social.technet.microsoft.com/Forums/en-US/8a47c9af-7654-4569-9baa-88c3c49fda8d/single-server-configuration-550-5754-smtp-unable-to-relay-recipient-in-nonaccepted-domain?forum=Exch2016MFSM
2. https://communities.bmc.com/thread/158536?start=0&tstart=0
3. http://techgenix.com/mail-relay-exchange-server-2016/ (See figure 4 about half way down... Creating a Receive Connector to allow relay to external addresses…)
4. https://practical365.com/exchange-server/exchange-2016-smtp-relay-connector/