This wiki is using two anti-spam features:
Proxy blocking prevents the creation of an account from an address listed as an open proxy. Or if the account was already created, before the Proxy blocking started working or from a not listed address, blocks the saving.
The black list extension blocks the page saving if it contains any of the urls listed in the Wikimedia black list.
If there is a URL that is not in the Wikimedia black list enter it in this Wiki's custom black list
First, go in the Recent Changes page. Several different situations can occur for a vandalized page:
The user that vandalized the page should be blocked. Simply go in the Recent Changes page, and select block near the user name ( sysop only) to go to the Block user page. Enter Indefinite in the Expiry field and a comment in the Reason field. Click on the Block this user button.