Email Validation Functionality:
    Create a utility function to validate email addresses. This function should check for proper formatting and potentially check if the domain exists.
    Utilize the existing email_helper.py utility module, or create a new module if necessary.

Integration with Sharing Logic:
    Modify the sharing functionality within the ShareChatService class located in app/modules/conversations/access/access_service.py to incorporate the email validation functionality before attempting to share the chat.
    If the email fails validation, provide appropriate error messages to the user.

Update API Documentation:
    Ensure any API routes related to sharing chats document the requirement for email validation, including expected error messages for invalid inputs.

Create Unit Tests:
    Add unit tests to verify that the email validation works as intended.
    Tests should cover various scenarios, including valid and invalid email formats.

Potential Challenges:
    Consider potential edge cases in email formats.
    Ensure that validation does not significantly impact performance during high-concurrency situations.

Code Consistency:
    Follow existing styles and patterns used in the project.
    Comment code appropriately, especially the parts handling error messages for validation failures.