emails being sent to icloud.com addresses being rejected

Contact icloudadmin@apple.com to open a deliverability ticket.

If you followed our best practices and reviewed your mail logs for more information but still can't diagnose and address delivery issues, you may contact our postmaster team by sending an email to icloudadmin@apple.com with all of the following information:

Your company name

Your email domain

The IP addresses of the affected mail servers

The SMTP errors that you're getting from iCloud mail servers

A detailed description of the issue, including when it started