Connect your own Resend account and every email AI Sync sends to a lead goes out from your domain: automations, appointment confirmations and reminders, and replies your team sends from the Inbox.
Eric Smith <eric@dunesmedicalspa.com>
When the lead replies, the answer lands on that lead's conversation in the Inbox, Eric gets a notification, and any automation that was waiting for a reply moves on.
Resend email uses your Resend plan. AI Sync doesn't bill or count it. Resend has a free plan for low volume.
✅ Before you start#
- You're the account owner in AI Sync.
- You have a Resend account (free to create at resend.com).
- You can sign in to wherever your domain's DNS is managed: GoDaddy, Cloudflare, Namecheap, Google, Squarespace or similar.
- Your domain is a business domain. Gmail, Yahoo, Outlook, iCloud and other free addresses can't send through Resend.
🧭 Set it up#
Create a Resend API key
In Resend, open API Keys and click Create API key. Choose
Full access (a "Sending access" key can't add domains or turn on replies).
Copy the key. It starts with re_.
Paste it into AI Sync
Go to Settings → Integrations → Resend and click Connect Resend. Paste the key and click Connect.
AI Sync checks the key with Resend before saving it. It's stored encrypted, and only its last 4 characters are ever shown again.
Pick or add your sending domain
- Already verified a domain in Resend? Pick it under Domain and click Use this domain. You're sending.
- New domain? Open Add a domain, type it (like
dunesmedicalspa.com) and click Add domain. AI Sync shows the DNS records Resend needs.
Add the DNS records
Add each record at your DNS host with the Copy buttons, so nothing is
mistyped. There are usually three: one TXT (the signature), one MX
and one TXT for the send subdomain.
Then click Check now. Each record shows Found or Not found yet. DNS changes can take a few minutes to an hour. Sending starts by itself as soon as Resend verifies the domain. You don't need to come back.
These records sit on a send. subdomain and a resend._domainkey name. They
don't touch your website or your normal email.
Turn on replies
In Resend, open Emails → Receiving, click the three dots, choose
Receiving address and copy it (it ends in .resend.app). Paste it under
Get replies in the Inbox and click Turn on replies.
AI Sync creates the webhook in your Resend account for you. From now on each lead's emails carry a reply address that's unique to their conversation.
Send a test email
Click Send test email. It goes to your own login email, exactly the way your lead emails go out: same From, same reply address. Check your inbox (and spam folder the first time).
👤 Who the email comes from#
| The lead… | The email comes from |
|---|---|
| Has an assigned rep | The rep: Eric Smith <eric@yourdomain.com> |
| Has no assigned rep | Your business: Dunes Medical Spa <hello@yourdomain.com> |
| Gets a reply someone typed in the Inbox | The person who typed it |
How each rep's address is made:
- If the rep's login email is already on your domain, that's their address.
- Otherwise it's their first name:
eric@. If two people share a first name, the person added later gets first and last name:eric.jones@. Accents are dropped (José→jose@). An existing rep's address never changes when you add someone. - The page shows each teammate's address under Who your emails come from.
You can change the business address (hello) and business name on the same
page. An automation step's own From name still wins over all of these.
These addresses don't need to be real mailboxes. Replies go to the lead's conversation in the Inbox, not to the From address.
↩️ What happens when a lead replies#
- The reply lands on that lead's conversation in the Inbox, even if they answer from a different email address.
- Only their new words show on the conversation. The quoted earlier email is kept but hidden.
- The rep who owns the lead gets a notification.
- An automation paused on Wait for reply moves on right away, and Stop when they reply stops the automation.
- When you answer from the Inbox, your reply threads under theirs in Gmail and Outlook.
🚫 Unsubscribes#
Automation emails carry an Unsubscribe link that Gmail and Outlook show next to the sender. When a lead clicks it, their contact is marked Do not email, and no automation or Inbox email goes to them again. Contacts you've marked Do not email (or Do not contact) are never emailed either.
❓ Troubleshooting#
| You see | Do this |
|---|---|
| "This key can only send email" | Create a new key with Full access and paste it under Replace the key. |
| Records stay Not found yet | Check the record name. Some DNS hosts add your domain to the end automatically: enter send, not send.yourdomain.com. Wait an hour, then Check now. |
| "Free email domains can't be added" | Use your business domain. Gmail and similar can't be sent from by anyone but Gmail. |
| Status Needs attention | The key was deleted or revoked in Resend. Paste a new one. |
| Want to stop using Resend | Click Disconnect. Email goes back to how it was sent before, right away. |