Email infrastructure for developers, and for AI agents.
A developer-first email API with a built-in AI agent, drop-in Resend and Loops compatibility, and deliverability that shows its working.
7
SDKs
[
The problem
]
Sendflit replaces the separate tools you’d otherwise pay for.
Sendflit
Developer platform
Before Sendflit
Separate tools for API, marketing, and testing
Painful migrations between providers
Deliverability scores with no explanation
Problems found after customers notice
With Sendflit
API, broadcasts, and automations in one place
Resend and Loops compatible APIs
A score of 100 with a named fix for every point
A daily briefing of what needs attention
[
The outcome
]
Everything you’d pay a separate tool for, built in
One account for transactional email, marketing, deliverability checks, and an AI agent that works alongside you.
[
Product
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Built for developers and AI agents
An email API, an agent, and the checks that keep your sender reputation safe.
A daily account briefing
Home lists what needs attention today, each with a fix.
An AI agent built in
Ask it to “announce the new pricing to active trial users next Tuesday morning” and approve the proposals it hands back. Claude and other agents connect through the MCP server.
Deliverability that shows its working
Every domain is scored out of 100: 50 for DKIM, SPF, DMARC and MAIL FROM setup, 50 for reputation. Every lost point has a named fix.
Autopilot for broadcasts
Test up to four subject lines, then send the winner at the best time.
100%
60%
40%
20%
0%
Winner
[
How it works
]
Switch from Resend or Loops by changing a key and a base URL
Your existing SDK calls keep working, including batch, scheduled sends, and webhooks.
Step 01
POST /resend/emails
Swap the key
Point your Resend SDK at /resend, or Loops at /loops/api/v1.
Step 02
domains · contacts
Import
Bring domains, contacts, templates and suppressions from Resend, or contacts from a Loops CSV.
Step 03
score: 100/100
Verify
Follow the named fixes until your domain scores 100.
Step 04
smtp.sendflit.com
Send
Use the API, the SMTP relay, or let the agent draft your next broadcast.
[
Scale
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Safety that protects your sender reputation
Risky sends are stopped before they go out, with a plain-language reason every time.
Checks before every send
Unverified domains are refused, broadcasts are screened, and bounces and complaints are handled automatically.
Subject-line tests
Up to 4
Subjects tested on a sample before the winner goes out.
Screened broadcasts
Phishing and spam patterns are flagged before sending, each with a clear reason.
Retries that
Never double-send
Idempotency keys on send and batch.
Developer-first details
SMTP relay, scoped API keys, HMAC-signed webhooks, and llms.txt docs.
SHIP WITH CONFIDENCE
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Security
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Security you can check, not just trust
The safeguards behind every account, key, and link.
Keys
sha256(key) · argon2id
Hashed API keys
Keys are stored as SHA-256 hashes, shown once, and scoped full, sending or read. Passwords use Argon2id.
Links
POST /unsubscribe · hmac
Signed links
Click and unsubscribe links are HMAC-signed, and unsubscribing is a POST, so link scanners can’t unsubscribe your recipients.
Tenants
GET /emails/:id → 404
Tenant isolation
Cross-tenant lookups return 404, so ids can’t be enumerated.
Webhooks
signature: verified
Verified webhooks
SES and billing webhooks are signature-verified, and the app refuses to start in production with an unsafe config.