You can reach out to a candidate in two ways: Request Interview and Chat.
This will send the candidate a request to interview for a particular position (which you will select via a drop down). They will see either the generic or custom Interview Message that you set up. See here for more details.
Candidates receive a text (in our experience, it's the best way to reach them!) or an email if we don't have their phone number on file.
Chat is a way to reach out and talk to candidates. You can ask or answer questions, discuss what to expect during the interview, reschedule, or anything else. As a best practice, a lot of our clients will send out an Interview Request and then follow up via Chat to those who have not replied.