Hello @Sumit Bera,
Based on your description, I understand that you would like to receive an email notification whenever a user is added or removed from any Azure Security Group.
Currently, there is no built-in, single-click option in the Azure Portal to enable email notifications for Security Group membership changes. Email notifications are only available for Microsoft 365 groups through the expiration policy.
Group expiration policy quickstart - Azure AD - Microsoft Entra | Microsoft Learn
One way to achieve this is by configuring Azure Monitor Alerts. However, before setting up alerts, you need to create and configure an Azure Log Analytics Workspace.
Azure Log Analytics will allow you to send Microsoft Entra Audit logs, enabling you to query changes. You can then create a custom query to trigger an alert whenever a user is added or removed from a Security Group.
For detailed steps on this setup, please refer to the following resources, where similar requests have been addressed:
Azure Tech Community Discussion
Stack Overflow – Azure Alerts for Group Changes
I hope this information is helpful. Please feel free to reach out if you have any further questions.