You can create a smtp mail server in SAP and you can send e-mail in SAP System.
Step by step mail server configuration in SAP
1- Create Default Domain
Tcode > SCOT
2- Create SMTP Node
TCode > SCOT
3- Create Schedule Job
Tcode > SCOT
4- Configure Mail Address of Users
Tcode > SU01
5- Send Test Mail
Tcode > SBWP
6- Monitor Mail Queue Status
Tcode > SOST