What’s the difference between Apple’s Mail app and iCloud.com filtering?

Apple's Mail app and iCloud.com webmail apply different filtering contexts that can produce varied results. The Mail app on iOS and macOS is an email client that displays messages from iCloud (or other configured accounts), while iCloud.com is the web interface to iCloud email specifically.

Filtering for iCloud email happens at Apple's servers regardless of how users access their mail. Whether checking via the Mail app, iCloud.com, or third party clients, the same server side filtering applies. However, the Mail app's Privacy Protection features (MPP) are client side, affecting tracking but not filtering.

Users accessing non iCloud accounts (Gmail, corporate email) through Apple Mail experience filtering from those providers, not Apple. The distinction matters for understanding where filtering decisions originate when troubleshooting deliverability to Apple device users.