3477480 - Outbound email failed with error "421 4.3.2 Service not available"

• Outbound email failed to be sent due to Message no. XS751 or XS612.
  
  
• Following error is recorded in Long text and SAPConnect trace. 
  
  Message cannot currently be transferred to node SMTP due to connection error.
  
  Message no. XS751
  
  Diagnosis
  
  The message was processed correctly in the SAP system. Due to a technical fault, the connection to the server mailserver.port could not be established or was interrupted.
  
  System Response
  
  The system has marked the message for a resend attempt. The message has not yet been sent.
  
  Information from external system (if available)
  
  421 4.3.2 Service not available
  
  Procedure for the administrator
  
  Check the connection from the SAP system to node SMTP.
  
  
  

• Currently no delivery to joe.doe@sap.com
  Message no. XS612

  Diagnosis
  The message could not be delivered to recipient joe.doe@sap.com. The following reason was given by the node (in the node language):

  
  421 4.3.2 Service not available

  System Response
  Processing was completed normally.

  Additional information of the used node (if available, in the system language of the node):
  421 4.3.2 Service not available

  Procedure
  Attempt to resend the message at a later time.

• SAP Netweaver release independent
• SAP S/4HANA release independent
• SAPConnect interface

Message no. XS751, XS612, 421 4.3.2, Service not available, SMTP, SOST, SCOT, SAPConnect , KBA , BC-SRV-COM , Communication Services: Mail, Fax, SMS, Telephony , Problem