The men join and get lots of messages from female members (who are not real) and are asked to upgrade to either read or reply to the messages. (thedatingdirectory.co)
Send lots of messages (no cut and paste though, they must be unique to the individual). (hookupland.com)
It's free to message once per 10 mins unless a girl is receiving lots of messages at the current time. (nomadphilippines.com)