[Logician]

2 points:

1- It is impossible to ban them all because of services like everyone.net. By using such services every domain owner can turn his domain to a free email provider for free so it is impossible to track them all.

2- It is not a very good idea to have a very long banned list in vb options because all these options are assigned to a variable individually in every call for a vbulletin page. And if your banned email list is say "50000" chars, it means that one of your variable will have a size of 50 Kb. and it takes that much space in the server, everytime global.php is called. Improper use of server resources..

I don't know how vb3 is handling this but I think it would be much performance friendly to save such options in a seperate place and call them only when they are needed (ie in register page and in user email change page).