581 votes29 comments · Office 365 Security & Compliance » Spam & Phishing · Flag idea as inappropriate… · Admin →
ATP does not consider mails from other Office 365 tenants, or even mailboxes inside of your tenant, as safe. The best way to put a stop to this is to follow the recommendations in SecureScore for your tenant; and report phishing mails to us promptly. Also, make sure that the sender is not allowed either by the tenant configuration or the user safelist.Tyler Bell commented
Microsoft has little to no threat intelligence for phishing attacks. This is only a rampant issue for 365. It does not happen on this scale with G Suite.