Resend

The Resend app sends your store's notification emails through your own Resend account, from an address on your own domain. It uses the notification templates you already have in Settings > Notifications, so there's no second set of templates to keep up to date.

Each email the app covers has its own setting, and Custom notifications sends other notification templates on events you choose. An email is sent through Resend only after you turn off Swell's own version of it.

Install Resend from the Swell App Store, and set it up in your test environment before the live one.

Each email has a setting in Apps > Resend > Settings, and uses the template of the Swell notification in the last column.

An email is sent through Resend when its setting in the app is on and Swell's own version is off. For most emails, you turn Swell's version off in Settings > Notifications. Shipping and abandoned cart emails are turned off differently. While Swell's version is on, the app skips the email and logs that Swell's email is still on, so customers never get both. If Swell's version is off and the app's setting is off too, neither Swell nor the app sends the email.

The app checks Swell's version each time it sends. To switch an email back to Swell, turn Swell's version on again.

Swell's own Shipping confirmation and Shipping update have no switch in Settings > Notifications, so the app skips them until you turn Swell's versions off through the Swell API. Swell sends its own shipping emails when you check Send email confirmation to customer on a fulfillment. To turn them off with the Swell CLI, find the notification's ID, then set enabled to false:

swell api get "/:notifications?model=orders&name=shipped.v2"
swell api put /:notifications/<notification ID> --body '{"enabled": false}'

Repeat both commands for shipped-update.v2, and add --live in the live environment. Saving Settings > Notifications afterwards keeps them off. To switch shipping emails back to Swell, set enabled to true. Once Swell's versions are off, the app sends a shipping confirmation for every shipment that isn't a draft, whether or not Send email confirmation to customer is checked. It sends a shipping update when a shipment's tracking number is set or changed, and not for other edits.

Swell sends its abandoned cart emails while the Abandoned cart switch in Settings > Notifications is on. To send the abandoned cart email through Resend, turn off the Abandoned cart switch and click Save changes. Swell then sends no abandoned cart emails, including follow-ups, and the app sends one email for each abandoned cart that has a customer account and items.

Each email uses the notification's subject, content fields and template as they are when the email is sent, so your edits in Settings > Notifications apply to the next email. The record is loaded with the same related data Swell loads for its own email, and the logo and Primary color come from Branding in Settings > Notifications.

Each notification in Settings > Notifications has an optional From email and BCC emails, and the app uses them:

To send another notification through Resend, add a row under Custom notifications in Apps > Resend > Settings:

The notification must belong to the same kind of record as the event: an order. event sends an order notification, a subscription. event a subscription notification, and so on. A shipment. or payment. event looks for a shipment or payment notification, so it can't send an order's shipping or refund email.

Custom rows don't check whether Swell also sends the notification. Turn off Swell's version yourself, or the customer gets two emails.

When Resend can't be reached, rate-limits the app or has a server error, the app fails the event and Swell delivers it again later, for up to about 4 days. Each email is sent with a key that Resend keeps for 24 hours, so an email that was delivered isn't sent again when the event is retried within that time.

When Resend rejects an email, for example because of an invalid API key or a From Address on a domain that isn't verified, the error is logged and the email isn't retried. Fix the setting; later emails are sent normally. A failed email doesn't stop the other emails for the same event.

Settings are in Apps > Resend > Settings and are saved separately for each environment.

The app logs each email it sends or skips, and each error, in lines that start with Resend:. In the Swell dashboard, the logs are under Developer > Console > Logs.

The app's setting for that email is off. Turn it on in Apps > Resend > Settings and click Save settings. If Swell's own version is off too, no email is sent at all.

Enter the API Key and From Address in Apps > Resend > Settings and click Save settings. No email is sent until both are set.

Swell still sends this email, so the app skipped it. Turn off Swell's version in Settings > Notifications and click Save changes. The log quotes the template's own label, which can differ from the name in Settings > Notifications, for example Order Receipt for Order confirmation. For abandoned carts, the rest of the line says to turn off the Abandoned cart switch. For shipping emails, it says to set enabled to false through the API. See Shipping and abandoned cart emails.

Swell sends no shipping emails for draft shipments, and the app sends a shipping update only when an edit sets or changes the tracking number. The email isn't sent, and there's nothing to fix.

Swell sends abandoned cart emails only for carts with a customer account and items, and the app does the same. The email isn't sent, and there's nothing to fix.

No notification with that name belongs to the event's kind of record. For a custom notification, check that Notification name is the notification's name, not its label, and that the notification belongs to the same kind of record as the Trigger event.

The record has no address in the field the notification sends to, for example a cart without a customer email. The email isn't sent.

Resend rejected the email, and the message after the status code says why, for example an invalid API key, a From Address on a domain that isn't verified, or an invalid address in a notification's BCC emails. Fix the key in Apps > Resend > Settings, verify the domain in Resend, or correct the BCC emails in Settings > Notifications. These errors aren't retried, so the email isn't sent.

Resend rate-limited the app, had a server error or couldn't be reached. Swell delivers the event again later. A 429 can also mean your Resend plan's daily or monthly limit was reached.

A custom notification sends a notification that Swell also sends. Turn off Swell's version in Settings > Notifications. For abandoned carts, leave the Abandoned cart switch off.

Swell's Liquid filters other than currency and img_url aren't supported. To compare, send Swell's version from the notification's Test email tab in Settings > Notifications.

Uninstalling the app removes its functions and settings, so emails stop going through Resend. Swell's own notifications that you turned off stay off, and customers get no email for them until you turn them on again in Settings > Notifications. To keep emails going, turn Swell's versions back on before you uninstall: the Abandoned cart switch for abandoned carts, and enabled set to true through the API for shipping emails. The app skips them from then on. Uninstalling applies to the environment you are in, so remove the app from the test and live environments separately.

Emails already sent stay in your Resend account. If you no longer need the API key, delete it in Resend under API Keys.

Every function calls the same handler. It reads the notification config from /:notifications by name and model, because names such as canceled.v2 and invoice.v2 exist on more than one model. A built-in email is skipped unless the config's enabled is false. recovery.v2 is also sent while abandoned_cart.enabled in /settings/notifications isn't true. The record is loaded with the config's query.expand, and the HTML is fetched from content.html.url, with a cdn.swell.test host replaced by cdn.swell.store, and rendered with the browser build of liquidjs. The render context is the record plus store (/settings/store with the logo, logo width, footer and store_color from /settings/notifications, which defaults to #614ed0, and name and support_email from /:clients/:self when /settings/store has none, then from from_name and reply_to), content (the rendered fields) and the data Swell's own emails get through $notify.data: refunds, shipment or invoice.

Emails are sent with POST https://api.resend.com/emails and an Idempotency-Key of swell-resend/<event type>/<event id>/<model>.<name>. The config's from, or the deprecated replyto, is the from when its domain matches from_email, and the reply_to otherwise. Its comma-separated cc and bcc are sent as cc and bcc. Network errors, 429 and 5xx responses are rethrown so Swell retries the event. Other 4xx responses are thrown with retry: false. The app has no models, content views or $app fields.

Swell builds and maintains the Resend app. For help with the app, email support@swell.is. For questions about your Resend account, domains or sending limits, contact Resend.