Interesting. Sent an email to a gmail user. Got a DMARC report back from hotmail (and gmail, but that's expected). The user has gmail forward mails to their hotmail account. Gmail spoofs the "From" address when forwarding. The result is that hotmail receives something that fails SPF (which is understandable because the gmail servers aren't listed as authorized senders on my end).

All of this makes sense, but I was puzzled for a moment when 1) I received a DMARC report from hotmail when I knew I didn't send any emails there, and 2) hotmail said SPF failed while gmail said it was fine.

#