[Bug] Backend support for newsletter subscription feature.

[Nonso024]

Description: On the front-end users encounter an error when attempting to subscribe to the newsletter from the blog page. The back-end system needs to be reviewed and updated to handle the newsletter subscriptions.

Acceptance Criteria:

1. Ensure that the backend processes the newsletter subscription requests correctly.
2. Validate email addresses and handle invalid inputs with appropriate error messages.
3. Confirm successful subscription by adding the email address to the newsletter subscriber list in the database.
4. Provide appropriate feedback to the front end in case of success or failure.

Requirement:

• Review the API endpoint responsible for handling newsletter subscriptions.
• Implement necessary validation and error handling for incoming subscription requests.
• Store subscribed email addresses securely in the database.

[johnson-oragui]

@Nonso024

Kindly include the team for this fix.