[#5454] New User registration

Do you have CB Auto Actions installed? If so disable it and see if the issue goes away. Maybe you've an action misconfigured and are causing an infinite loop of activateUser being fired.

Auto Actions isn't even installed

I have Default Language, Default, CB Core, CB Menu, CB Connections, CB Articles published

Private Message System, CB Forums, CB Blogs and CB Antispam are installed but not published. Especially CB AntiSpam as it doesn't work.

Then I've no idea what's going on. CB has nothing in its core that could do this. It'd specifically have to have been coded (3rd party), modified, or setup (using CB Auto Actions) to do this. It seams like registration is getting stuck in a loop, but I don't see how. PM backend super administrator login credentials and can take a look.

Checked activateUser further and we've a caching check in place to block resending of the moderator email if it's sent already. So even calling it on a loop can't cause this unless it was done in separate processes (e.g. ajax calling it over and over maybe). Very strange issue. That email can also send when a user confirms their account, but it's subject to the same caching since that's also handled in activateUser function. If possible please PM backend super administrator login credentials and will take a look.

Have reviewed your install and I can't see any cause for this. I've found 2 major issues with your install, which are likely the result of your migration.

Your ACL appears to be seriously broken. I've corrected the Super User permissions and access the best I could, but there's still some things that are not quite right. For example Super Users can't reach your VIP Page, which is restricted to Registered users, despite their View Access Level having the Registered usergroup selected (even directly having the Registered usergroup does not fix this, for my user at least). This could be caused by the following issue.

Next running CB > Tools > Check Users Database finds a massive amount (hundreds) of invalid usergroup mappings. Those mappings are most likely causing duplicate moderator rows to show up when parsing to send moderator emails, which is why your moderator is getting so many duplicates. You'll need to clear out those invalid entries, which CB can attempt to do this for you by running the "Check Users Database" tool in CB > Tools. Please make a backup for attempting to click the fix links.

Once done retest and see if the duplicate emails are gone. This isn't a step I can perform for you as you need to backup your database first to be safe.

After the repairs we worked on the user is still getting 150+ emails when someone registers.