1. Folded part that covers the opening

2. Printed stationary used for professional correspondence

3. Large quantity of envelopes

4. Adhesive for sealing the envelope

5. Person who receives the envelope

6. Postal service for international delivery

7. Location to submit envelopes for mailing

8. Comprehensive list of contents inside

9. Items enclosed in the envelope

10. Location information of the recipient

11. Sticker with recipient's details

12. Measurement of heaviness of the envelope

13. Opening to insert the letter

14. Material used for making envelopes

15. Portion of the envelope with transparent material

16. Evidence of mailing or receipt