Runearc for saaS teams
App email and the support inbox, in one product
Runearc sends your product's email through a Resend compatible API and runs support@ as a shared inbox your team works from. One set of domains, one set of keys.
What gets in the way
The sending bill grows with every user, and support@ lives in a separate help desk with its own seats.
How it goes
- 1
Change the base URL
POST /v1/emails takes Resend's request body. Keep your code, swap two env vars.
RESEND_BASE_URL=https://api.mailbay.dev/v1 - 2
Point support@ at Runearc
Conversations open in a shared inbox. Assign them, reply as support@, close them.
support@ · assigned to you - 3
Listen for events
Signed webhooks for queued, delivered, bounced, complained and received, or a WebSocket stream.
message.delivered message.received
The switch is two lines
If your app sends with the Resend SDK today, this is the migration. Fields Runearc does not support are refused with a fix, never silently dropped.
RESEND_BASE_URL=https://api.mailbay.dev/v1
RESEND_API_KEY=mb_live_xxxxxxxxx # a Runearc Sending only keyTested with resend 6.32.1 in a Next.js 16.4 route handler.
await fetch("https://api.mailbay.dev/v1/emails", {
method: "POST",
headers: {
Authorization: `Bearer ${process.env.MAILBAY_API_KEY}`,
"Content-Type": "application/json",
},
body: JSON.stringify({
from: "Acme <noreply@acme.com>",
to: "ada@example.com",
subject: "Your receipt",
html: "<p>Thanks for your order.</p>",
}),
}); // { id: "eml_..." }message.queued message.delivered message.deferred
message.bounced message.complained message.failed
message.scheduled message.canceled message.receivedEach delivery is signed; the webhooks docs have the check in Node and Python.
Works with what you use
Every tool, with what we tested, is in the integrations directory.
What you get
Resend compatible sending
Same request body, batches of up to 100, scheduled sends and idempotency keys.
Resend alternativeA shared support inbox
Assign conversations, close and reopen them, and reply as support@. Your team can also use Apple Mail or Outlook over IMAP.
Roles per project
Admin, Developer, Support and Viewer, with inbox access per teammate. Support can read and reply, nothing else.
Roles, as agencies use themReceived mail is free
Inbound mail and support replies never count toward the sending allowance.
Traceable delivery
Every recipient gets an accepted, deferred, bounced or complained status, including the provider response when it is safe to show.
SMTP error reference
Questions
How much code changes when we move from Resend?
For sending with the Resend Node SDK: two environment variables, RESEND_BASE_URL and the key. Fields Runearc does not support yet are refused with unsupported_field and a fix, so nothing is dropped silently.
Can the support team use their own mail app?
Yes. Each inbox can have app passwords for Apple Mail, Outlook or Thunderbird over IMAP and SMTP. Replies sent there stay in the same conversation.
How do we hear about bounces?
Register a webhook for message.bounced and the other message events. Each request is signed, and the event carries the receiving server's reply.
Is there a contract or an SLA?
Not yet. Runearc is currently free. The planned paid plans are on the pricing page.
Want the long version? Read Runearc vs Resend and sending from Next.js, or see who else Runearc is for.
Put Runearc to work
Get inboxes, sending, your own domains and MCP in one workspace. The free plan includes 3 inboxes, 3,000 emails a month and 3 custom domains, with no card.