Some of the roles are quite hard to fill and for such positions, you might not get the number of applications you had expected. In such a case you can go ahead and contact the candidate you want to be a part of this position.
With the help of sourcing for hard-to-fill roles mail template you can check which candidates you wish to send this mail to and hence increasing the number of applications that you receive in a day.
Subject: Hiring for [position name]
Dear [candidate name],
We are looking for a [position name] who can join us on our current project and according to your profile and experience, it shows that you are a great match for the position.
You see we recently had accomplished [accomplishment] and we are looking for someone who would like to be a part of further accomplishments.
So let us know if you are interested in this role and if you do, we can schedule a 10-minute call to discuss this further.
Looking forward to your reply.