Too many registration attempts error on forum, and not receiving emails when registering

I am quite a lot getting this too many registration attempts and also for when signing into one of my accounts on my forum.

Another issue I am facing is when I create an account I am not receiving the verification email I am supposed to get for when I register a new account. Anyone got any ideas?

Thanks for the report. Two separate issues here, and I can point you at both.
Emails not arriving
This is almost certainly SMTP. If it isn't enabled in your forum's settings, Flatboard falls back to PHP's native mail() function. On most shared hosting that function will happily report "success" without actually delivering anything, because there's no real mail server behind it to do the sending. It's a limitation of mail(), not a Flatboard bug.
To fix it:

1. Go to admin/config, then the SMTP section, and enter your real SMTP server details (host, port, credentials).
2. Use the built-in "send test email" button there to confirm delivery actually works.
3. If it still fails, check your server logs. A failed SMTP auth or connection will log an explicit error there, which is more useful than the generic message shown to the user.
   In the meantime, anyone who registered but didn't get the email can request a new one from the login page without opening a new account. See /resend-verification.
   "Too many registration attempts"
   This one's worth checking your setup for. Registration is limited to 3 attempts per hour, per IP, but every attempt counts toward that, including ones that fail on a wrong captcha answer, a stale form (expired CSRF token from a tab left open), or a typo. It's easy to burn through 3 in a row without anything malicious going on.
   More importantly: is your forum sitting behind Cloudflare, another CDN, or a reverse proxy / load balancer from your host? If so, and the proxy's IP isn't declared as trusted in your server-side config, every visitor's request looks like it's coming from the same IP as far as the rate limiter is concerned. That means the 3-attempts-per-hour quota gets shared across your entire forum's traffic, not per visitor, which would explain hitting the limit fast even with just a couple of people trying to sign up.
   Can you confirm whether you're behind a proxy/CDN? If so, I'll walk you through adding its IP to the trusted list so real visitor IPs get used instead.