All ESPs
Transactional
Resend
Resend offers SMTP, SDKs, and a modern API. Authentication uses two TXT-style DKIM records plus an SPF include and a return-path CNAME.
DNS records to publish
| Type | Host | Value |
|---|---|---|
| TXT | send | v=spf1 include:amazonses.com ~allSPF (subdomain) |
| TXT | resend._domainkey | k=rsa; p=<public key>DKIM public key |
| MX | send | feedback-smtp.<region>.amazonses.comBounce / feedback (subdomain) |
Authentication setup
SPF
Resend publishes records for the 'send' subdomain you authenticate, including the SPF entry.
DKIM
Publish the TXT record Resend generates.
DMARC
Standard rollout; subdomain-based architecture keeps the root domain DMARC clean.
Deliverability tips
- Authenticate as a subdomain (e.g. send.example.com) so your root domain DMARC posture stays separate.
- Use the React Email components and the broadcast API for marketing rather than transactional flows.
- Monitor bounce and complaint webhooks from day one to catch list quality issues early.