[sincerely]

Sorry for asking but are you familiar with how MS Excel aggressively converts data to dates? There's no way to "sanitize" it (without resorting to hacky solutions like including extra characters) and even if you fix the data, it will re-change them to dates the next time you open the file.

[jaywalk]

You're simply incorrect. If you set the column format to Text it will never convert data to dates, including when you open the file.

[zozbot234]

Great, how do you set a custom column format in a CSV file?

[ryukafalz]

I'm only familiar with LibreOffice and not Excel myself, but: if you want to be sure a column is treated as text in a CSV file, you have LO quote text fields on save, and have it treat quoted fields as text on import. I assume Excel must have similar options.

[rini17]

LibreOffice, on opening of CSV file, always pops an import dialog where you can do this. To keep the column format permanently, save as ods.