bbpress registration just uses wordpress registration, so likely a site/wordpress issue
copy/paste of my standard advice on email – hopefully it will help
1. You should be aware that many spam filters strip messages that do not come from the correct address. So if your site is mysite.com and your email address
in wordpress settings>general is email@example.com then it is likely that messages will be dumped in transit.
You need to set up email to come from your site eg firstname.lastname@example.org, your hosting provider can help if needed.
2. Just bbpress?
Then you need to see if this is wordpress wide or just bbpress.
it could be a theme or plugin issue
As a test switch to a default theme such as twentyfifteen, and see if this fixes.
If that doesn’t work, also deactivate all plugins apart from bbpress and see if this fixes. if it does, re-enable one at a time to see which is causing the error.
If you cannot do this to your site (say because it is live) then use the ‘troubleshooting’ features of this plugin to let you test without affecting other users
Health Check & Troubleshooting
Next try switching to smtp email – this page from the host Siteground explains it
and of course
By default, you do NOT receive emails for your own topics/replies, only if somebody else replies on your subscribed topics
so testing would need two email accounts to prove !
If you wish to use a different default restriction message for your forums and topics you can customize them from Paid Member Subscriptions -> Settings -> Content Restriction.
These restriction messages are helpful if you want to have a different marketing copy for forums and topics, leaving the other restricted content with the marketing copy you already have in place.
Hope this helped you.
Thanks both! this has been very useful. I have one more question, when I get the email registration confirmation, the email comes from wordpress.org, how do I change these settings so the email comes from my own domain?
there are several plugins that do this eg
CB Change Mail Sender
or you can google for code