Is datebook.net Safe?

This domain is one of more than twenty apparently-related domains that host what are supposedly signup pages for 'dating sites'. These domains are advertised by unsolicited emails containing deceptive text such as "[name] just posted to your timeline. Click here to see it." It is unclear exactly what the purpose of these sites are. They may be intended simply to collect email addresses and other information about visitors so that they can be targeted for more advertising. Alternatively, they may be gateways to the type of site that makes its money by upselling premium subscriptions or charging to exchange messages with other 'members' ('members' of such sites are often computer-generated using scripts).