1. Future Relationship: Optional section expressing interest in future collaboration or continued service, used when there's potential for ongoing business relationship

2. Specific Achievements: Detailed metrics or specific accomplishments, used when quantifiable results are available and appropriate to share

3. Team Recognition: Acknowledgment of team members involved, used when the service involved multiple contributors

4. Testimonial Permission: Request for permission to use the letter as a testimonial, included when organization wishes to showcase the service publicly

1. Service Summary: Optional attachment detailing specific services rendered, included for complex or long-term service arrangements

2. Performance Metrics: Optional attachment with specific performance data or success metrics, used in formal business contexts where quantifiable results are relevant

3. Project Documentation: Optional attachment with relevant project highlights or milestones, included for significant or long-term service engagements