iDRAC Settings -> Network -> Common Settins
Register iDRAC on DNS - check
DNS iDRAC Name - hostname
Static DNS Domain Name - domain.com
[Apply]
Server -> Alerts -> SNMP and Email Settings
SMTP (Email) Server Address Settings
SMTP (Email) Server IP Address or FQDN / DNS Name - mail.domain.com
Enable Authentication - check
Username - hostname@domain.com
Password - *****
SMTP Port Number - 587
[Apply]