According to a LinkedIn survey, only 15 percent of candidates are not even open to considering a new job. That means an overwhelming 85 percent ARE open to a new position, maybe via a recruitment email.
In such a scenario, if your email campaigns are not getting at least 45–50 percent conversions it is quite likely that you are doing it wrong.
More information: http://recruitingdaily.com/want-create-irresistible-recruitment-email-heres-6-sneaky-hacks-help/