I would like to make sure that all the documents will be arrived on her hand before Wednesday.
Dear Khun Kai,
Thank you for your email ka.
Please be informed that she will come into Thailand on Sunday. Therefore, I want to make sure that all the documents will reach her within Wednesday, so she can submit the application on Thursday morning and get her visa on Friday.
If it is not possible, please let me know. I will need to re-schedule her start date and inform her team header.