I had that happen to me with my Kellogg interviewer last year. I sent a hard copy thank you letter to her at the admissions office mailing address, since I had no idea who would be checking the generic admissions email address.
I thought of that after I posted, so I did the same thing this morning. Sounds like it was the right choice.
"Egotism is the anesthetic that dulls the pain of stupidity." - Frank Leahy
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