I frequently received requests to connect on LinkedIn from recruiters I do not know. I decline all connection requests from people I don’t know.
If you’re a recruiter and you want to contact me, please either use the ‘send a message’ functionality on LinkedIn or just send me an email.
When I asked a recruiter friend why so many recruiters used connection requests instead of messages, he pointed out that it costs money to send more than a handful of messages per month. If you’re a recruiter, pay the money to get the messages functionality. It doesn’t seem very professional to me to have you misusing LinkedIn functionality because you’re too cheap to pay for the appropriate functionality.
</end of grouchy old man rant>