Deliverability

Sending to Apple Private Relay

Reliably deliver to @privaterelay.appleid.com (Sign in with Apple's Hide My Email). Register your sending domains — including MailBlastr's return-path subdomain — and from-addresses in the Apple Developer Portal, and authenticate with SPF and DKIM.

If your app supports Sign in with Apple, users can choose Hide My Email. Apple then assigns each user a unique, randomly generated address under @privaterelay.appleid.com and forwards mail from it to their real inbox. Apple will only relay mail from senders it recognizes — so a few configuration steps are required, or your messages bounce.

Apple offers two Hide My Email services: one through Sign in with Apple, and one through iCloud+. This guide covers Sign in with Apple, which generates a unique address for account creation and login. Configure it in the Apple Developer Portal under Certificates, Identifiers & Profiles → More → Sign in with Apple for Email Communication → Configure.

Register your sending domains

Apple requires you to list every domain you send from. If your return-path (envelope) domain differs from your visible sending domain, you must register that too.

With MailBlastr the return-path runs through a subdomain, so it differs from your visible From domain. Find it in your Domain settings — it's formatted as send.yourdomain.tld (or send.yoursubdomain.yourdomain.tld) for the MX and SPF records. Register both your primary domain and this send. subdomain as Apple email sources, or relay mail will bounce.

Register your email addresses

Alongside your sending domains, Apple requires registration of every from-address you use to send from those domains. Add them one by one or as a comma-separated list. If you also send to Private Relay from sources other than MailBlastr, include those addresses as well.

Authenticate your sending domains

Apple requires SPF and DKIM. Because MailBlastr mandates SPF and DKIM for every domain that sends through it, a domain that is Verified in MailBlastr already meets Apple's authentication requirement. See DNS records.

Still seeing bounces from @privaterelay.appleid.com?

Relay bounces don't always carry a detailed reason. The common causes are:

The user deleted their Hide My Email address in Apple settings.
The user exceeded the daily limit of 100 emails to/from their Hide My Email address.
A misconfiguration — double-check that every sending domain (including the send. return-path subdomain) and every from-address is registered and authenticated with Apple.

Apple lets the account owner and admins in the Apple Developer Portal opt in to notifications when relay delivery fails — enable that to catch problems early. For more, see Apple's docs on configuring the Private Email Relay service and communicating using the Private Email Relay service.