Adapty Mail needs a stable customer_user_id and an email for every user it delivers to. Wire both up in your app code before launching a campaign.

Collect user emails

Two values must reach Adapty per user: a stable customer_user_id that identifies the user, and the email itself. Identification has to come first — without it, Adapty has no profile to attach the email to.

1. Identify the user. Pass a stable ID — your backend user ID, Firebase UID, or similar — either by passing it as customerUserId to .activate() at SDK startup, or by calling Adapty.identify() later (for example, at login). Either way, the ID must be set before any paywall is shown.

   Platform guides: iOS, Android, React Native, Flutter, Unity, Kotlin Multiplatform, Capacitor.

2. Pass the email. As soon as the user provides their email, send it to Adapty via updateProfile using the email parameter.

   Platform guides: iOS, Android, React Native, Flutter, Unity, Kotlin Multiplatform, Capacitor.

Verify your email coverage

After implementing collection, check coverage in Adapty:

1. Go to Customers → Profiles.
2. Filter by profiles that have an email set.

Target at least 30–50% email coverage among your active users before launching your first campaign. You don’t need to wait for 100% — launch as soon as you reach 30%. Users who provide their email later are automatically enrolled in active campaigns when they qualify.

Email collection strategies

Most apps don’t collect emails by default. Pick the approach that matches your app’s current state.

Strategy	Best for	How it works
Existing authentication	Apps with any form of login	You already have the email — pass it to Adapty after the user authenticates. See the auth-method reference below for where to read it.
Email gate before the paywall	Apps without auth — health, wellness, astrology, photo editors	Add a single email input screen between onboarding and the paywall. Conversion typically runs 70–90% because users have already invested time.
Web paywall builder checkout	Minimal SDK work; email captured on web	The first screen of the web paywall builder collects the email and passes it to Adapty — useful for users who click a campaign before an in-app gate is live.
Onboarding step	Quiz-based onboarding (fitness, nutrition, education)	Place an email input 2–3 steps into onboarding. Frame it as value delivery (“We’ll email your personalized plan”) and avoid making the step skippable.
Server-side API import	Apps with an existing email list on another platform	Use the Update profile endpoint with email and external_profile_id to match records to existing profiles.

Limitations

• Anonymous users: Users without a stable customer_user_id can’t receive campaigns. Identify them when they create an account or log in — from that point, any email they provide is matched to their Adapty profile.
• Users without an email: Profiles with no email are excluded from campaign delivery and don’t appear in campaign analytics. As soon as they provide an email, they become eligible for future campaigns.