had some users sign up with email addresses from free disposable email address services and came up with a list of some of the more popular domains that host such services. These users are 99-100% of the time signing up just to spam, which is why they want to use a quick temporary address. That's the problem with services like this. They encourage spam more than they help it.

If you want to limit members to people with real email addresses and not just temporary ones used just to confirm at registration, I suggest you ban the following emails:

@mailinator.com, @mailexpire.com, @mytrashmail.com, @spamhole.com, @jetable.org, @spamgourmet.com, @dodgeit.com, @sneakemail.com, @trashmail.net, @pookmail.com, @spamspot.com, @e4ward.com, @greensloth.com, @kasmail.com, @mailnull.com, @spamday.com, @spam.la, @spammotel.com, @tempinbox.com, @willhackforfood.biz

Feel free to add to this list!

There's still hotmail and gmail, etc, but many people use those for their primary email addresses. I wouldn't suggest blocking them.

UPDATE:

These domains belong to vbulletin options ->'user banning options'

Here is the currently updated list of disposable service domains:
https://github.com/disposable/disposable
https://raw.githubusercontent.com/disposable/disposable-email-domains/master/domains.txt
But it is 144K domains! Which i have doubts will vbulletin can work with such list.

This other list contains just 550 items:
https://gist.github.com/michenriksen/8710649 (raw list)

To convert that list to vbulletin format, items needs to be separated by space not line breaks.
1. Open https://textmechanic.com/text-tools/basic-text-tools/addremove-line-breaks/
2. click C button
3. paste domain list to upper text area
4. add one space to the field that is after the text "and replace the line break with this text:"
5. click REMOVE ALL LINE BREAKS button
6. copy the result into vbulletin AdminCP -> vbulletin options ->'user banning options' making sure "Enable Banning Options" is set to Yes.

Btw. there is some old plugin that may help too: https://www.vbulletin.org/forum/showthread.php?t=210946