Hi,

       To use email alerts, you need to first configure SEPM to use your mail server, then configure the alerts as needed.

Configure SEPM to connect to the mail server

In the Symantec Endpoint Protection Manager console, click Admin.
Click Server.
Select which Symantec Endpoint Protection Manager that you want to send alerts from.
Click Edit Server Properties.
In the Server Properties dialog box, click the Mail Server tab.
Enter the IP address, host name, or domain name of the email server in the Server Address text box.
Enter the user name of the account on the email server in the User Name text box.
In the Server Properties dialog box, enter the password of an account on the email server in the Password text box.
Click OK.

Configure email alerts

Click Monitors.
Click Notifications.
Click the View Notifications tab.
Click the Notification conditions tab.
Click Add.
Choose the event that you want to be alerted of...such as Virus definition out-of date.
Enter the requested information in the window that pops up.
Click OK.

Also try the following :-

- Log in to the SEPM
- From the Admin tab -> Servers -> Server name -> Edit server properties -> Mail server tab
- Click on the "Help" button and input the name as "User@domain-name.com"(As an example.). The name used has to be a valid user name that belongs to the domain.