Outbound email with Resend
Resend lets your app send email: newsletters, receipts, welcome messages, and campaigns. This page covers when you actually need it, how to connect it, and what your app can do once it is connected. Before you set it up, check the callout below, because the most common email need on Instroc does not require an email integration at all.
Every Instroc Cloud project includes a built-in Inbox. When a visitor submits a contact form, feedback form, or waitlist signup, the message lands in your Inbox and you are emailed automatically, at no cost and with nothing to connect. Messages can be up to 5,000 characters. Resend is only for email your app sends out to other people. See the Backend overview for how the Inbox works.
What Resend is for
Connect Resend when your app itself needs to deliver email to your users or customers. Typical cases:
- Transactional email, like order confirmations, booking reminders, and receipts.
- Newsletters and campaigns sent to a list of subscribers.
- Notifications your app sends when something happens, like "your report is ready".
If the only email you need is "tell me when someone fills in my form", stop here and use the Inbox instead.
Connecting Resend
Resend is a key-based integration, available on the Pro and Business plans. Create an API key in your Resend account (it starts with re_), then open your project's Workspace view, go to Integrations, and open the Resend card. The card's Get API Key link takes you to the right place in Resend, and the Requirements section lists what you need. Paste the key into the connect form and you are done.
Your key is stored server-side and is always shown redacted in the product. Roc never asks for keys in chat; if a build needs Resend, Roc points you to the Integrations panel instead. See the Integrations overview for how connections work in general.
The from address must be verified
Email your app sends must come from a verified sender in your Resend account. Verify your domain (or sender address) in Resend first, then use that address as the from address. If you ask Roc to send from an address Resend does not recognize, delivery will fail, so it is worth doing this step before you wire up any sending.
What your app can do
Once connected, ask Roc for the sending behavior you want. Your app can:
- Send to a single recipient or a list of recipients.
- Send in batches of up to 100 emails at a time.
- Send HTML or plain text bodies.
- Set reply-to, cc, and bcc addresses.
Example prompts:
When an order is placed, email the customer a confirmation with the order details. Send from [email protected].
Add a newsletter signup. Once a week, send subscribers a digest of new posts.
Scheduled and triggered sending
Email does not have to be sent the moment a user clicks something. Sending runs through your app's serverless functions, so it can be triggered by events in your app or run on a schedule, like a weekly digest or a reminder the day before an appointment. Describe the timing you want and Roc sets up the function and the schedule. See Functions for how functions work.
Billing
Emails your app sends through Resend count as integration calls and bill to your Instroc Cloud usage, not your AI credits. Email actions run under tighter rate limits than other integration calls. Rates are listed on the Cloud billing page. Resend's own plan limits and pricing apply on their side, since the sending happens through your Resend account.
SendGrid as an alternative
Prefer SendGrid? It works the same way: create an API key in SendGrid (it starts with SG), open the SendGrid card in the Integrations panel, and paste the key. SendGrid also supports template-based emails. Like Resend, it requires a Pro or Business plan, and calls bill to your Cloud usage. Pick whichever provider you already use; your app's email features work the same either way.