Safe to delete old email folders in ~/Library/Mail/v6?

I’m on macOS Mojave 10.14.6 and noticed in ~/Library/Mail/V6 that I have 6 mail folders but have only 4 email accounts setup. It seems that 2 are old accounts that I have since deleted in Internet Accounts but the emails are still on my hard drive. Would it be safe to assume that I can delete those folders? Would there be any other places that I should look for remnants?