Make it clear to candidates that you’re not canceling the interview. Suggest a new date and time, unless you don’t know when you will be able to reschedule. In that instance, let them know you will get back to them as soon as possible.
Sample email to reschedule interview
Subject line: Rescheduling interview for the [Job_title] position
Unfortunately, we need to reschedule our interview for the [Job_title] position that we had arranged for [date and time.]
[Briefly explain why you’re rescheduling, e.g. Due to unexpected personal obligations, our hiring manager [Hiring manager’s name] won’t be available on that day.]
Are you available [new date and time]? If this doesn’t work for you, let me know a better date and time.
I apologize for any inconvenience.