I don't think so. I see @facebookmail.com in SPAM folders way more often than you'd expect on both Office 365 and GSuite. I also see mail from Microsoft and Google filtered into SPAM on their own platforms once in a while.
facebookmail.com is not in the alexa top 500, whereas facebook.com is.
spam filters really are this dumb at big companies. usually the way we'd get around it is we'd call up $big_company and say, "hey, could you please remove our e-mails from your spam list? we would like to send your users a lot of mail right now." a few hours later, we'd be good to go.
this was ~2007. it may be harder to get them on the phone now, and the value of your company may need to be higher (we only had a few hundred million, which seems like chump change these days).
