EDIT: I'm putting this up front so it's the FIRST thing you see and read: I WAS WRONG I ASSUMED (and I know better) that it wasn't possible for me to have 3000 accounts created within a day or two of going live. I ASSUMED what I saw was accounts that were NOT local, I WAS WRONG I created a process to remove the bot accounts from my database without crashing my site. I have tested and it looks like all functions are working. If you need help because you suddenly have thousands more accounts than you would suspect ask me for the procedure. I'll gladly provide it.
I was able to identify bot accounts by looking at creation times. They accounts are grouped by "batches" where the account creation times are within seconds of each other. That's not typically going to happen with random humans creating accounts.
I used a tool to see how many users my site had. Once I saw the count was larger than expected, I wondered who these users were. I checked the database table and saw a huge list. I know for a fact that all these users are not on my instance. I was able to confirm that the database includes email address and password hash. This SHOULD mean that if someone tries to login, and their authentication information is sitting in my database, they can login at my site locally, correct? I only ask because I did not find an entry anywhere that lists a “home” instance for them to log in to. Am I correct in understanding that accounts are distributed like communities are?
Ok, I've looked at the source provided and don't see an e-mail field either. The account e-mail is also limited to your own instance, correct? This thread was making me mildly concerned that e-mails were being shared when federating between instances.