Hi Swatik, thank you for your valuable input.
I had checked the email was already configured by the previous IT.( I follow the steps on the link you give.)
But I had checked the web page for NS-50, there are recent alarms.
But I am not receiving any email.
And the alarm listed on the web page, was at critical level but I did not received the email.
Any ideas, why the firewall is not sending email?
SMTP is configured correctly and also the email address.