Postmark Transactional Email
Send transactional email through Postmark on the right stream, with bounces tracked.
What it adds
A Postmark delivery path that separates message streams, honours suppression, and retains provider identifiers for diagnostics.
What your agent is told to do
5
What your agent is told to do
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Put Postmark behind the app's existing mail layer as one adapter, so no calling code constructs a provider-specific payload. This entry is an alternative to the other transactional email integrations, not an addition — pick one adapter and keep the mail layer identical.
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Classify every outbound message as transactional or broadcast and bind that classification to the matching message stream at the mail layer, so the choice is made once and cannot be got wrong at an individual send site.
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Send from the app's background-job system and persist the provider's message identifier on the record the moment it comes back, so a support question about one email can be answered without guessing.
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Consume delivery and bounce feedback on a verified endpoint and maintain a suppression state per address that every send checks before queueing.
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Do not send transactional mail to an address the provider has marked inactive just because the app still has it on a user record. Reconcile the app's view with the provider's suppression state and surface the problem to the user instead.
Edge cases it handles
8
Edge cases it handles
8- Sending a broadcast on the transactional stream, or the reverse, degrades deliverability for everything else. Bind the stream to the message classification centrally rather than passing it in at each call site.
- An address the provider has deactivated after repeated bounces or a complaint will silently stop receiving mail. Detect the inactive state, show the affected user that their address is not receiving mail, and give an operator a way to reactivate after the address is corrected.
- Delivery and bounce webhooks arrive on a public endpoint and can be replayed. Verify their authenticity before trusting them, and apply them idempotently so a repeated event does not double-count a bounce or overwrite newer state.
- A job retried after a timeout may resend an email that already went out. Key each send on a stable identifier so the retry reconciles rather than duplicating.
- Provider message identifiers are the only reliable way to trace a specific email in a support conversation. Store them alongside the message record and keep them for as long as support needs them.
- Transactional mail must not be gated on marketing consent. A receipt or a password reset goes to someone who has unsubscribed from everything else.
- Non-production environments must not reach real recipients. Suppress delivery or redirect every message to a fixed internal address by default outside production.
- When the provider is degraded, the triggering action must still succeed, the message must stay queued for retry, and no log line should carry the credential or the full body.
Definition of done
8
Definition of done
8- Every message is classified and sent on the stream matching its classification, decided in one place.
- Provider message identifiers are stored on every sent message record.
- Bounce and delivery webhooks are authenticated and idempotent.
- Suppressed or inactive addresses are skipped before queueing and surfaced to the user.
- Retried jobs never produce a duplicate email.
- Non-production environments cannot deliver to real recipients.
- The feature matches the existing design system.
- No existing functionality is broken.
Related features
Firebase Cloud Messaging
Firebase Cloud Messaging
Deliver push through Firebase with registration tokens that stay valid as devices change.
What it does
A Firebase-backed push channel with server-side token lifecycle management, consistent payload handling across platforms, and safe handling of the routes a notification opens.
How it works
- 1 Store one record per device registration, tied to the account signed in at the time, the platform it came from, and when it was last confirmed working, and let one account hold many of them.
- 2 Send from the app's existing background-job system with the provider credentials held server-side, and treat every send as a job that can be retried rather than work done inline during a request.
- 3 Decide, per notification type, whether the payload is meant to be displayed by the platform or handled by the app, and keep that decision the same on every platform. The same event behaving as a visible alert on one platform and a silent update on another produces bugs nobody can reproduce.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/firebase-cloud-messaging
OneSignal Push Notifications
OneSignal Push Notifications
Send push notifications to the right devices, with user preferences respected.
What it does
A push delivery path through OneSignal covering subscription registration, audience targeting, per-channel preferences, and delivery outcomes recorded against the app's own records.
How it works
- 1 Find the events the app already notifies on by email or in-app, and treat push as another channel for those same events rather than a separate notification system with its own triggers.
- 2 Record the link between a push subscription and an account on the server, established at sign-in and severed at sign-out, so a device that changes hands does not keep receiving the previous user's notifications.
- 3 Hold the provider credentials server-side and send every message from the app's existing background-job system, so a slow or failing provider never blocks a web request.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/onesignal-push-notifications
SendGrid Transactional Email
SendGrid Transactional Email
Send account and product email through SendGrid and keep the delivery feedback.
What it does
A SendGrid delivery path for account email, with validated template data and recorded bounce and complaint outcomes.
How it works
- 1 Route transactional mail through the app's existing mail layer with SendGrid behind it as one adapter. The rest of the codebase must never construct provider-specific payloads directly, or swapping or adding a provider later means touching every send site.
- 2 Enumerate the app's transactional messages — verification, password reset, receipts, alerts — and give each a template with a declared set of variables that is validated before the message is queued.
- 3 Send from the app's background-job system with a stable per-message identifier, and store the provider's message identifier on the record as soon as it is returned so support can trace a specific email later.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/sendgrid-transactional-email
How it works
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Copy the link
Grab the Markdown instruction URL for this feature.
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Give it to your AI
Paste it into Claude Code, Cursor, v0, Lovable — whatever you build with.
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It inspects, then implements
Your agent reads your existing app first, then adds the feature to fit it.
Works with your stack
These instructions are written to adapt. They tell the agent to detect your framework, match your existing design system, and reuse what you already have — rather than assuming a particular stack.
Need it tighter than that? Customize the feature and tell it exactly what you're running.