Email validation — Sendara docs

Bounces hurt your sender reputation. Sendara can check a recipient before you send: it validates the syntax and confirms the domain can receive mail via a DNS/MX lookup (with an RFC 5321 implicit-MX fallback for domains that publish an A record but no MX). You can run the check inline on a send, or stand-alone.

Validation confirms a domain can accept mail — it does not guarantee the specific mailbox exists or that the message will be delivered. It is a cheap, high-signal filter against typos and dead domains, not a delivery promise.

Validate during a send

Add validate_recipient: true to POST /v1/send. The check runs before the spend gate, so an undeliverable recipient is never charged and never queued — it is rejected up front.

curl https://api.sendara.dev/v1/send \
  -H "Authorization: Bearer sk_live_xxx" \
  -H "Content-Type: application/json" \
  -d '{
    "channel": "email",
    "idempotency_key": "rcpt_9f21",
    "message_type": "transactional",
    "destination": { "email": "[email protected]" },
    "metadata": { "from_email": "[email protected]" },
    "payload": { "subject": "Hi", "body_html": "<p>Hello</p>" },
    "validate_recipient": true
  }'

validate_recipientbooleanOptional

When true, the recipient is checked before the send is charged or queued. An undeliverable address is rejected with recipient_undeliverable (422). Default false.

An undeliverable recipient comes back as a 422:

{
  "error": {
    "code": "recipient_undeliverable",
    "message": "recipient address is undeliverable: domain cannot receive email (no MX or A record)"
  }
}

Validate without sending

To check an address on its own — at signup, on form submit, or while cleaning a list — call POST /v1/validate.

curl https://api.sendara.dev/v1/validate \
  -H "Authorization: Bearer sk_live_xxx" \
  -H "Content-Type: application/json" \
  -d '{ "email": "[email protected]" }'

emailstringRequired

The address to check.

{ "email": "[email protected]", "valid": true, "reason": "" }

When the address fails, valid is false and reason explains why (e.g. invalid email syntax or domain cannot receive email (no MX or A record)).

How it behaves

Fails open.A transient DNS error or timeout never blocks a send — only an authoritative “domain does not exist” result is treated as undeliverable.
Cached per domain. Lookups are cached briefly, so validating many recipients on the same domain stays fast and does not hammer DNS.
Opt-in. Sends are never validated unless you ask — existing integrations are unaffected.

Pair validation with suppression: validate at capture time to stop typos entering your list, and let automatic suppression handle addresses that go bad after a real bounce.