Sounds like you’ll either have to make an email for each bot or make them on an instance that doesn’t require emails to sign up.
Or, if you use Gmail, you could use your own email with a + alias. For example: If your email is you@gmail.com then you could use you+bot@gmail.com as the boy’s email. It should be treated as unique by Lemmy (I have not yet checked), and all mail sent to it will automatically be tagged as Bot.