I hope this email finds you well. My name is Tran Thanh Thuong from Vietnam. My paper has been accepted for presentation at the upcoming conference. I have also paid the registration fee.

I kindly request an official invitation letter. This document is essential for processing the necessary paperwork at my university to facilitate my participation in the conference. 

Please send me the invitation letter as soon as possible as the event is next week.

Thank you for your attention to these matters. I look forward to your prompt response.

Warm regards,

Tran Thanh Thuong