Improvement: Refactor Email Notification System

[AArchange]

trafficstars

Description: Refactor the email notification system to enhance reliability and ensure timely delivery of notifications for invoice status updates and payment confirmations. Tasks: Review and optimize the current email notification system. Implement retry mechanisms and logging for failed deliveries. Test notifications across different scenarios. Acceptance Criteria: Email notifications are reliably delivered. Users receive timely updates on invoice status and payments.