1593121 - Error XS817 with text "No ESMTP Plug-In Is Available for SAPconnect" occurs in transaction SOST while sending Mails through SMTP node

In transaction SOST mails have status 817 and are not sent.

The error message text is:

• "Cannot process message in SAP System
   Message no. XS817
   ...
   No ESMTP Plug-In Is Available for SAPconnect
   Application Server Used by the Send Process:
   ..."
  
  
• "Cannot process message in SAP System
   Message no. XS817
   ...
   SMTP Plug-In Not Available
   Application Server Used by the Send Process:
   ..."

• SAP Basis Release 610 and higher
• SMTP node

Kein ESMTP Plugin verfügbar für SAPconnect, Vom Sendeprozeß verwendeter App.Server, Sendeprozeß auf App.Server mit Plugin einplanen, SMTP service, Internet Communication Manager, ICM, SMICM, icm/server_port_<*>, XS 817, No ESMTP Plug-In Is Available for SAPconnect, SMTP Plug-In Not Available,  Application Server Used by the Send Process , KBA , smtp plug-in is not available , BC-SRV-COM , Communication Services: Mail, Fax, SMS, Telephony , Problem