ZeroBounce.net accepts the most common file delimiters/separators, but their can be occasions where the file you want to validate has a different file delimiter then what's listed in our file delimiter drop down. We call these Custom Delimiters/separators.
What you can do is get a text editor, we recommend Notepad++, because it can handle large files and it's free to use. Open your file with Notepad++ and do a search (Your delimiter) and replace (With one of our accepted delimiters/separators). Save the file and attempt to re-upload it.
If you're still having problems uploading, click the "Leave a message" button under the "Help" icon after doing a basic search.