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Email communication and Apple Private Relay

Authentication and email communication serve different purposes in discover.swiss. The email address used to sign in is not necessarily the address a user wants to receive messages at, and successful authentication does not automatically grant permission to send emails.

This page explains which email address partners should use, how Apple's private email relay affects delivery, and what to consider before contacting users.

Login email and correspondence email

Address Purpose Important considerations
Login email (identity provider / authentication token) Identifies the user during authentication. Do not use it as the contact address. It may change or be an Apple private relay address.
Correspondence email (email property of the Person profile) Shared contact address for correspondence. It may differ from the login email. It is part of the central discover.swiss profile, meaning it is not tied to any specific partner.
Partner-specific contact email (managed by the partner) Communication intended only for a particular partner or application. Store and manage it separately, for example using partner-specific profile data, if it should not affect the shared profile.

Use the discover.swiss profileId to identify or match a user, rather than an email address. See Call Azure Active Directory B2C.

The correspondence email is shared

The email property belongs to the central discover.swiss Person profile. A change can therefore affect other applications or partners that use this shared address. Before updating it, clearly explain this to the user and ensure that the user intends to update their shared correspondence address.

If an email address is needed only for your application, consider storing it in partner-specific profile data or your own system instead.

Apple Sign in and private email relay

When users select Hide My Email during Sign in with Apple, Apple can provide an address ending in @privaterelay.appleid.com. Messages to this address are forwarded by Apple to an email address associated with the user's Apple Account, without revealing that personal address to the application.

These relay addresses are associated with the Sign in with Apple application or service registration. They should not be treated as a permanent, universal identifier across applications.

Detecting a private email address

The Person response from GET /me in the Profile API includes the Boolean property HasPrivateEmail. It indicates whether a private email address is associated with the profile (currently relevant to Apple sign-in).

Use this property to identify cases that may require special handling. It does not indicate that the user has consented to receiving messages, and it does not replace checking the correspondence email address and its intended use.

See Profile service endpoints – Person / me.

Sending emails to an Apple relay address

Apple only forwards messages from appropriately registered and authenticated email sources. Because Sign in with Apple is integrated through the central discover.swiss login, the relevant Apple registration is managed by discover.swiss, rather than by each partner's B2C client application.

  • Email sources used by discover.swiss for its own transactional messages are already registered.
  • If a partner needs to send messages directly to an Apple relay address from a different sender address or domain, the sender must first be reviewed and registered by discover.swiss.
  • Apple requires sender authentication using SPF and/or DKIM and checks the registered sender information. Registering a domain does not by itself guarantee delivery.

Contact discover.swiss support before using an additional sender. Please describe the sender address or domain, the types of messages to be sent, and the legal basis for contacting users.

For the technical requirements, see Apple Developer – Configure private email relay service.

Permission to contact users

Neither signing in nor providing a correspondence email address is, by itself, permission to send every kind of email. Partners remain responsible for determining and documenting the appropriate legal basis and communicating the intended purposes to users.

  • Transactional or service-related emails, such as order confirmations and information needed to fulfil a booking, may generally be sent when necessary for the service and otherwise lawful.
  • Marketing or other optional communications, such as newsletters and promotional offers, require an appropriate legal basis and, where applicable, specific consent and an unsubscribe mechanism.
  • Acceptance of terms and conditions does not automatically constitute valid consent for every purpose. Check the content of the terms, any separate consent collected, and the applicable requirements.

A correspondence email address and a consent or communication preference are different pieces of information. Manage any partner-specific communication preferences and consent records separately from the shared Person.email field.

  1. Read the current profile. Use GET /me to retrieve the user's Person profile, including the correspondence email and HasPrivateEmail.
  2. Determine the purpose. Check whether the intended message is necessary for a transaction or requires a separate permission or consent.
  3. Use the appropriate address. Prefer the profile's correspondence email for permitted communication. Do not silently substitute the email address from the authentication token.
  4. If a contact address is missing or unsuitable, ask the user. Explain what messages the address will be used for. If the address is only for your app, keep it partner-specific.
  5. Only update the shared correspondence email intentionally. With the user's knowledge, update the Person.email property using PATCH /me. Consider appropriate address verification before relying on a newly entered address.
  6. If you must use Apple's relay, coordinate the sender. Contact discover.swiss to check sender registration and perform delivery tests before going live.

Tip

The login email and the correspondence email do not need to be identical. A user can keep an Apple private relay address for login while providing a different correspondence address for permitted contact.