Unable to relay recipient in non-accepted domain, error when trying to send an email

kbt155446

Issue

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 eWORKFLOW 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, MessageBodyReadere] messageBodies) at SourceCode.MessageBus.Server.MessageBusRuntime.SourceCode.MessageBus.IMessageDestination.Send(String title, MessageExtendedInformation extended, IEnumerable`1 attachments, MessageBodyReaderR] 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/