This is a popular issue and this issue has not any relation to wpForo.

All processes of user registration and email sending belong to WordPress core functions. wpForo only provides a nice registration form, it doesn't have any affection on the whole user registration process.

However, we know lots of cases and solutions that could help you. Please check these points one by one before opening a new support topic:

1. Check your Spam / Junk folder. In most of the cases your website emails go to Spam folders because the "From Email" is not used correctly or your server IP address is listed in email blacklists.

2. Disable all other plugins and test it again. This is the next popular issue. There are lots of plugins which may affect  the email sending process. For example, some SMTP plugins, or antispam plugins like Cleantalk for Anti-Spam can filter outgoing emails.

3. Make sure your server email sender works well. Make sure you receive emails from your WordPress (on registration or on other cases...). You can check it in Dashboard > Forums > Tools > Debug > Errors & issues admin page. If the mail function doesn't work you'll see an error notification.

4. Install SMTP plugin. The new one is Post SMTP. Do a test email sending via Post SMTP. Check the logs of all sent emails. If you see the email is sent, then this is email receiver service issue, use other email address from other providers (gmail.com, yahoo.com, hotmail.com...) to register and test.

5. Some shared hosting services, or some Antispam plugins try to cache emails and those are not being sent immediately. You should wait 1-30 min (e.g.: on some GoDaddy hosting plans you receive emails in 45 min).

6. If you're using GMail Fetch services, go to Gmail Settings > Accounts and Import and click on "Check mail now" link to load all new comments from website email server.

7. Make sure the "Anyone Can Register" option is enabled in WordPress Settings > General page.

8. Make sure the "Enable User Registration email confirmation" option is enabled in Dashboard > wpForo > Settings > Login & Registration admin page.

9. Disable wpForo and use the WordPress native registration form to test. The native registration form can be found with this URL. Make sure you're logged out, this URL is only available for guests:

yourdomain.com/wp-login.php?action=register

After checking all these points, we recommend you contact to your hosting service and ask them check your server email logs. They should check and help you fix this issue.

As an alternative, you always have a chance to change the user registration type and disable the "Email Confirmation" step by disabling the corresponding "Enable User Registration email confirmation" option in Dashboard > wpForo > Settings > Login & Registration admin page. So your users can register without email confirmation. The password fields will be displayed on the registration form. They just need to fill the Username, Email, and Password fields and register. Here is the wpForo user registration form "with email confirmation" and "without email confirmation":