Fix an issue regarding import csv file in tinyEmail

I need help resolving an issue with tinyEmail. Following should be done:

There is a csv file that needs to be imported in tinyEmail but i get an error.
Probably there are letters in the file that are not allowed.
The goal is to provide an updated csv file that can be imported at once.
The file has 4 columns.
The file has to be tested before within TinyEmail so it will work at once.

Ideal skills and experience:
- Familiarity with GrooveFunnels and tinyEmail and cloudflare
- Expertise in troubleshooting email delivery issues
- Ability to interpret and resolve custom error messages