Resend Transactional Email
Send application email through Resend with verified domains and tracked delivery.
What it adds
A Resend delivery path with domain verification gating production sends, controlled attachments, and recorded delivery events.
What your agent is told to do
5
What your agent is told to do
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Put Resend behind the app's existing mail layer as one adapter. This entry is an alternative to the other transactional email integrations rather than a companion to them; the mail layer, template contract, and suppression handling stay the same whichever adapter is in place.
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Gate production delivery on a verified sending domain. Until verification is confirmed, keep the app in a mode that redirects or suppresses delivery rather than sending from an unverified address into spam folders.
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Send from the app's background-job system, keyed on a stable per-message identifier, and store the provider's identifier on the record as soon as it is returned.
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Resolve attachments server-side from the app's own storage, enforce a size ceiling before the job is queued, and re-check that the recipient is entitled to the attached file at send time.
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Consume delivery and bounce events on a verified endpoint and maintain suppression state that every future send checks before queueing.
Edge cases it handles
8
Edge cases it handles
8- Sending from an unverified domain lands mail in spam and damages the domain's reputation. Treat verification as a precondition for production delivery, and show its state clearly to an operator rather than letting it fail quietly.
- Attachments have a size ceiling and are resolved from files the app controls. Check the size before queueing so an oversized file fails visibly at composition, and re-check access at send time so a file the recipient has lost permission to is not attached anyway.
- Asynchronous send jobs retried after a timeout will otherwise deliver the same email twice. Key each send on a stable identifier and reconcile the retry against the existing record.
- Provider identifiers and webhook events are what make a delivery question answerable. Store the identifier on the message record and process events on a verified, idempotent endpoint, since events can be replayed and can arrive out of order.
- Development and staging must never reach real recipients. Default those environments to suppressing delivery or redirecting every recipient to a fixed internal address, and do not rely on a data set being fake.
- Transactional email must not be conditioned on marketing consent, and marketing email must not be smuggled through this path to reach people who unsubscribed.
- Credentials and full message bodies must be absent from logs and error reports, because a captured reset link or one-time code is a live credential.
- When the provider is unavailable, the triggering action must still succeed, the message must stay queued, and the app must tell the user the email is on its way rather than claiming delivery.
Definition of done
9
Definition of done
9- Production delivery is blocked until the sending domain is verified, and verification state is visible to operators.
- Attachments are resolved server-side, size-checked before queueing, and access-checked at send time.
- Every message record carries the provider identifier.
- Delivery and bounce webhooks are authenticated, idempotent, and update suppression state.
- Retried jobs never send the same email twice.
- Non-production environments cannot deliver to real recipients.
- No log or error report contains credentials or full message bodies.
- 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
Postmark Transactional Email
Postmark Transactional Email
Send transactional email through Postmark on the right stream, with bounces tracked.
What it does
A Postmark delivery path that separates message streams, honours suppression, and retains provider identifiers for diagnostics.
How it works
- 1 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.
- 2 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.
- 3 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.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/postmark-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.