Alejandro Mayorkas actually said...

Based on my reading of the Inspector General's report, it appears that it was not.

I believe I did. In a conference call, I believe I did, to the best of my recollection.

I, as the leader of the agency, bear ultimate responsibility for the correctness of our decisions, our administration of the law.

To the best of my knowledge, official business is to be conducted on official Government email.