As always, the best defense here is to be wary of clicking on links from unknown users, especially poorly written ones. (tomsguide.com)
Unknown user rates are taken directly from incoming SMTP logs of participating ISPs, tracking how often an IP address attempts to send a message to an address which does not exist. (senderscore.org)
The arrival of Message Requests feature has replaced the «Other Folder» on Facebook Messenger that was only accessible from the Web and was available as a single place to store new requests that are sent from unknown users. (techone3.in)