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This guide is adapted from Apple’s article on bulk email sending best practices for iCloud Mail. Many of these recommendations also apply to Gmail and Outlook, so be sure to read How do I avoid Gmail’s spam folder? and How do I avoid Outlook’s spam folder?.
Apple does not offer allowlists or feedback loops for iCloud Mail. Your reputation as a sender is determined automatically based on how you send and how recipients engage with your email. The best way to land in the inbox is to follow the requirements below consistently.

Authenticate Your Email

Like every major mailbox provider, iCloud uses email authentication to confirm that you are who you say you are. Apple requires that bulk senders authenticate with SPF, DKIM, and DMARC.
AuthenticationRequires SetupPurpose
SPFNoProves you are allowed to send from this domain
DKIMNoProves your email originated from you
DMARCYesProves you own the domain and instructs how to handle spoofs
When you verify your domain with Resend, SPF and DKIM are configured and validated for you automatically, so your email meets Apple’s authentication requirements out of the box. Resend also signs every message with DKIM and handles SPF alignment on your behalf, so you don’t have to manage these records yourself. Apple additionally requires that your sending domain publish a DMARC policy. Action Items
  1. Verify your domain with Resend to set up SPF and DKIM automatically
  2. Setup DMARC for your domain

Use Consistent, Reputable Infrastructure

iCloud builds trust over time based on the domains you send from. Keeping your sending consistent helps Apple recognize you as a legitimate sender.
  • Separate your marketing and transactional streams so each can build its own reputation.
  • Maintain a consistent From: name and address so recipients (and Apple) recognize your brand.
  • Make sure your email is RFC 5321 and RFC 5322 compliant.
Action Items
  1. Use dedicated sending addresses for marketing vs. transactional email

Send Only to Recipients Who Opted In

Apple requires that you send only to recipients who explicitly subscribed to your emails. Purchased lists, rented lists, and email appends are not permitted and will damage your reputation. Prevent sending to recipients who:
  • Didn’t explicitly opt in to your emails
  • Show no signs of engagement with your emails
  • Requested to be unsubscribed
  • Marked your emails as spam (complained)
  • Never received your email (bounced)
Action Items
  1. Only send to recipients who explicitly subscribed
  2. Use Webhooks to remove bounced or complained recipients from your list
  3. Never resume sending to addresses on your suppression list

Make It Easy to Unsubscribe

Apple requires bulk senders to offer an unsubscribe link so recipients can opt out immediately. We recommend implementing one-click unsubscribe for the best user experience. Action Items
  1. Include a clearly visible unsubscribe link in bulk emails
  2. Add Unsubscribe Headers to enable one-click unsubscribe

Keep Your List Clean

iCloud monitors recipient engagement closely. Continuing to send to inactive or invalid addresses lowers your reputation.
  • Periodically remove inactive subscribers.
  • Handle bounces with a standard suppression policy.
  • Keep your spam complaint rate low.
Action Items
  1. Regularly prune inactive subscribers from your list
  2. Suppress bounced and complained addresses automatically

Monitor SMTP Errors

When iCloud rejects or defers a message, it returns an SMTP error explaining why. Apple expects senders to track both temporary and permanent errors and respond appropriately, rather than retrying blindly. Action Items
  1. Review your mail logs and Resend dashboard for SMTP errors
  2. Adjust your sending based on temporary (defer) vs. permanent (reject) errors

Still Having Issues?

Apple does not provide allowlists or feedback loops, but for unresolved delivery problems you can contact Apple at icloudadmin@apple.com. Include your company name, domain, the SMTP errors you’re seeing, and a detailed description of the issue.

Summary

Email deliverability is overwhelming. One way to simplify it is to think: what would a phisher do? Then do the opposite! iCloud’s goal is to only show emails that their users want to see. Reverse engineer phishing sending habits and consider how you could prove to Apple at each step that you clearly have no malicious intent.
Anything we missed? Let us know.