When you import a list with unknown headers, you can create field aliases to make it easier. You can also edit those aliases in field management. Check it out.
Admin Permissions Required
1. Under Admin, click Field Management.
2. Find and select the field you want to add an alias to.
3. Under Field Actions, click Edit Import Aliases.
4. Enter an Alias and click Save.
Click Add Another and enter more aliases if you need them.