iCloud Mail and the spam folder

iCloud Mail (icloud.com, me.com, mac.com) does not publish detailed sender requirements or a postmaster portal, so the best approach is to get the basics right and watch results.

#Basics that matter

• SPF, DKIM and DMARC pass and align: Verify a domain, DMARC.
• Valid reverse DNS and TLS on the sending servers (handled by usend on the platform's IPs).
• A sensible From name, and a subject that matches the content.
• Both html and text parts.

#Typical issues

• Rate limiting. Apple may defer mail from new or high-volume senders with temporary errors. usend retries, and you see delivery_delayed events. Do not resend the same message yourself; that adds load. See Warm up a domain.
• Hide My Email and private relay addresses. Many iCloud users receive mail through relay addresses. Those need extra care: Apple Private Relay bounces.
• Remote content. Apple's Mail Privacy Protection loads images in the background, so opens look higher than they are: Open-rate accuracy.
• Links. Long redirect chains and unfamiliar tracking domains look suspicious. Turn off click tracking for sensitive mail.

#When a message is in junk

Ask the recipient to mark it Not Junk, add you to their contacts and reply once. iCloud responds to those actions per user.

#Check what iCloud accepted

The email's events show delivered when Apple's server accepted it. A bounce with a 5.7.x code is a policy rejection: read the message in the bounce field and compare with Bounces and suppressions.

More: Why emails go to spam.