What you need.
01
A Resend account
02
A domain verified in Resend, with its DKIM and SPF records added at your DNS provider
03
A Resend API key, either Full access or Sending access
04
A From address on the verified domain
Steps
- Verify your domainIn Resend, open Domains and add your domain. Resend recommends a subdomain such as updates.example.com. Add the DKIM and SPF records it shows at your DNS provider and wait for the domain to verify.
- Create an API keyCreate an API key with Sending access, optionally limited to that domain, then copy it. Resend does not show the key value again.
- Add the connection in Sync NotifyUse smtp.resend.com on port 587 with STARTTLS. Enter resend as the username exactly, then paste the API key as the password.
- Test and sendRun Test and send with a From address on the verified domain. If your network blocks port 587, try port 2587 with STARTTLS or port 465 with SSL.
Settings to enter.
Sync Notify fills these in when you choose the Resend preset. They are here so you can check them.
RESEND PRESET
- SMTP host
- smtp.resend.com
- Recommended port
- 587STARTTLS: connects in plain text, then upgrades to TLS
- Alternative STARTTLS ports
- 25 or 25872587 is useful when standard SMTP ports are blocked
- SSL ports
- 465 or 2465Implicit SSL/TLS from the first byte
- Username
- resendThe literal lowercase word, not your account email
- Password
- Resend API keyFull access or Sending access
- Provider limits
- 10 requests/second per teamSMTP shares the API rate limit. The Free plan allows 100 emails a day and 3,000 a month; paid plans have no daily limit and a monthly quota set by the plan
Common errors.
ERR 01Authentication failed
The username is not exactly resend, or the API key was deleted, mistyped or is not active. Set the username to the literal word resend and paste a current API key from the API Keys page, or create a new one.
ERR 02Domain is not verified
The From address uses a domain that is not verified in Resend, or that differs from the domain the API key is limited to. Finish domain verification in Resend, then send from an address on that exact domain.
429Rate limit or quota exceeded
Your team sent more than 10 requests a second, or reached its daily or monthly email quota. Lower the per-minute limit in Sync Notify. For a quota, wait for the daily reset at midnight UTC or upgrade the Resend plan.