Company sounds really cool and I am very interested - what's with the email address? is it that string you posted "aXRzYXVuaXhzeXN0ZW0raG5AaXRlcmFibGUuY29t" @ iterable.com?
I don't mean to antagonize, since any more detail would give away the answer -- but a qualified candidate should recognize various encoding outputs, even if they can't immediately identify the specific encoding scheme.
"It's a unix system, I know this."