Tag Archives: Hub Transport

451 4.7.0 Temporary server error. Please try again later. PRX4

Issue: Mail Delivery to your Exchange 2013 Server is broken

“51 4.7.0 Temporary server error. Please try again later. PRX4” You will find this error on following situations:

  1. Trying a simple “Telnet fqdn 25” after input of data.
  2. On your Frontend Transport Server SmtpReceive Logs.
  3. On an extended Office 365 / Exchange Online Message Trace Log (Mails delivery stays in “pending” to your Hybrid Exchange 2013 SP1 Server (equal to PowerShell: Get-Messagtrace -Status Pending)
  4. Mail in OWA get stuck in your Drafts folder (OK, that can have many other reasons)

Solution: either…

a) Tony wrote already a very good blog about one clue: http://thoughtsofanidlemind.com/2013/03/25/exchange-2013-dns-stuck-messages/

b) …and that is a tricky one on the right hand and so simple on the other hand -> Check:

If your HubTransport is on “Draining” – perform this:

Mail delivery is back :-)

have fun, Alex