Candidates can sometimes miss an interview for various reasons. Ignoring such candidates is not always the best thing to do. Try to get an update from these candidates with an Interview No-Show Mail and let them know that your company is still interested in interviewing them.
Finding good candidates is no cakewalk. The candidates shortlisted for interviewing have definitely gone through an efficient screening process, hence, cancelling them because they missed an interview is not justified.
Subject: Interview at [Company_Name] for [Job_Title] position.
We had scheduled an interview with you at our office premises/on a video conference at [Time 00:00] today. We didn't get to see you today. We hope everything is fine with you.
Our hiring is still in process so let us know if you are still interested in the role, we can reschedule the interview.
If you are interested, kindly send us a follow-up email and we will discuss the possible timings for the next interview.