Hi Tracey,

Our company invested in LinkedIn Recruiter.  I gives full access to message individuals with LinkedIn profiles and a spectrum of supporting tools.  It's all geared toward engaging passive candidates.  For example, you can collect relevant profiles into "project folders" for current or potential openings.  You can then message them through LinkedIn. 

We are still learning to make full use of it but it has been a helpful tool to proactively reach out to passive candidates.

Sincerely,

Grace