Some things shouldn’t be said over SMS. (Here’s looking at you, relationship break-ups.) If a candidate has made it through a couple of rounds of interviews, you shouldn’t send a “We’re sorry, you didn’t get the job” text. That’s a phone call.
And use email to send sensitive documents like employment contracts, or to negotiate salaries. You can text them a heads up to check their email though.
But for quick and simple messages, like interview reminders, follow-ups, or job alerts, SMS for recruiting is ideal.