You want to enable the e-mail sending via SMTP from an AS ABAP-based SAP system.

Set the appropriate profile parameter for the ICM. 

Configure and activate an SMTP node using transaction SCOT (SAPconnect: Administration). 

Configure and activate the ICF service for SAPconnect using transaction SICF (Maintain Services). 

Create an RFC destination of type "T" to the external Mail Transfer Agent (MTA). 

Maintain a default domain using transaction SCOT (SAPconnect: Administration).