Before-save Apex Trigger:
This is the best solution because a before-save trigger runs before the record is saved to the database, providing an opportunity to validate or modify the data.
In this case, the Apex trigger can validate the email address using a regular expression or a third-party API call to ensure the email address is valid. If the email is invalid, an error message can be displayed using addError().
Why not the other options?
A . Submit a REST API Callout with a JSON payload:
REST callouts are more complex and generally not recommended for simple validation tasks like email format validation. Additionally, callouts cannot be performed directly in a before-save trigger.
C . Use a custom Lightning Web Component (LWC):
LWCs are primarily for UI interactions and should not be used to enforce data validations that are server-side requirements.
D . Use an Approval Process:
Approval Processes are for managing the approval flow of records, not for real-time validations. They cannot enforce email validation directly.
Reference:
Apex Triggers Documentation
Trigger Context Variables