As a matter of fact, you can do both. You can have the linkup to keep the links in a queue, waiting to be moderated like so: interface has changed since when the feature was first introduced but the functionality remains the same).

You can also remove/block any entries you want, like so :

Blocking entries can be done based on the entry email and/or URL

of course you can combine both methods.

One proven method is to avoid moderation at the beginning and set the linkup send you an email

when someone enters a link. This will allow you to check whether you get spam entries or not.

You can easily remove the entries from the email you receive and if the spammy person persists,

just block it from the dashboard completely.