Your Registration is Pending Approval emails sent multiple times

A site has been sending the 'Your Registration is Pending Approval' email from 2 to 5 times for each user within milliseconds for some users. 

There's no setting to config this so is this a bug and how can I stop it?

J 3.10.12
CB 2.11.0
PHP 8.2.29

Thanks

It only resends if they attempt to login while pending beyond that there's no code for it to resend multiple times. Are you sure those emails are coming from CB? Are they all identical and look like your pending email as configured in CB? Are those some users registered multiple times using alias email address (e.g. tom1+123, tom1+456)?

They are all being sent from the system to the same email address for each user.  I have screenshots but they contain personal data.

I've no idea. There's no functionality for doing that. I suppose a misconfigured mail server could maybe do that. If the emails are different then it's probably another extension sending an email. Do you have any auto actions acting on user registration events? If so try disabling those and retest. Did this start happening recently? If so what changed recently (e.g. install something new, updating something, etc..)?

Please keep in mind Joomla 3 is discontinued so support for it will be limited.

I'm aware of the outdated install but that's a different problem for another day 

The last 4 have different referrers according to the db. All sent in less than 1 minute.

Thanks

Ok, so yeah they're trying to login when they haven't been approved yet. This will send the pending email again. That's all completely normal.