I should add that I also have this hack installed which provides a notification like new PM's and allows SuperMods to take action (instead of just admin). The other bonus is that there is a "BAN" button rather than just a deleting the ones you don't want (which means the spammers can just reuse those email addresses again).
https://vborg.vbsupport.ru/showthread.php?p=2015393
Problem is that this mod only works if you turn on moderation for ALL users… What I wanted to do was make the option appear in the ModCP WITHOUT turning on the "Moderate New Members" option.
To fix this problem I found that editing the xml install file and the user_moderation.php file removing the references to $vbulletin->options['moderatenewmembers'] means this little hack doesn't check to see if the moderate new members flag is on, but still checks everything else and still only allows supermods access. (which is exactly what I want).
While I understand this isn't supported by the creator (Mosh), it's only a minor mod and is easy enough to reverse if ever needed.