Apple's new DMARC Policy and Gmail
Regarding Apple’s new DMARC policy we’ve been doing some testing.
From Gmail’s web interface, the described “fix” of entering your iCloud SMTP details works. But if I send via Gmail from Mail.app on macOS or iOS, mails “From:” my mac.com address go into the ether, presumably being caught by spam filters following the new "p=quarantine" flag set by Apple.
If that's the case, then it means that Gmail isn't attempting to send these via Apple's SMTP servers... for some reason? Why would Gmail process it differently if sent from the web vs. a Mail client?