Scenario: You want to send out emails using the SMTP but you also want to have a different from email addresses pr. user.
Solution: What we normally do is that we store the email on the user in SAP and we then get the email from there. So something like:
SQL: SELECT E_Mail FROM OUSR WHERE USER_CODE = '$[USERNAME]'
in the email "from" -field will get the email from the user in SAP.