Writing a thank you post-interview e-mail without 100% knowing names?

So I just had a panel interview with 3 people, over the phone, scheduled by HR.

I asked HR twice to know the name before the interview but it was not supplied. The interview went well and got to know their names, but not the spelling. I suspected they are also doctorates but that information was not provided either. Think names like: Cassandra, Kassandra, Steven, Stephen, just things like that.

I want to provide a post-interview thank you e-mail for their time and information but I sincerely do not want to begin an e-mail with:

To: Misspelled name, misspelled name, misspelled name.

What are my options?

Is: "To my Interviewers," far too impersonal?

What are alternative phrases I can possibly use.

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