Validation API

The Validation API lets you verify email addresses before sending to reduce bounces and protect your sender reputation.

Validate single email

Validate a single email address.

POST /v1/validate/single

Request body

Field	Type	Required	Description
email	string	Yes	Email address to validate

Example request

curl -X POST https://api.mailingapi.com/v1/validate/single \
  -H "Authorization: Bearer $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"email": "user@example.com"}'

Response

{
  "email": "user@example.com",
  "valid": true,
  "result": "deliverable",
  "checks": {
    "syntax": "valid",
    "dns": "valid",
    "mx": "valid",
    "disposable": false,
    "role": false,
    "catch_all": false,
    "smtp": "valid"
  },
  "suggestion": null
}

Result types

Result	Description	Action
deliverable	Mailbox exists	Safe to send
undeliverable	Mailbox doesn’t exist	Don’t send
risky	May bounce	Send with caution
unknown	Couldn’t verify	Manual review

Check fields

Field	Description
syntax	Email format valid
dns	Domain has DNS records
mx	Domain has MX records
disposable	Temporary email service
role	Generic address (info@, admin@)
catch_all	Domain accepts any address
smtp	Mailbox exists (SMTP check)

---

Validate with typo suggestion

When validation detects a possible typo:

{
  "email": "user@gmial.com",
  "valid": false,
  "result": "undeliverable",
  "suggestion": "user@gmail.com"
}

---

Batch validation

Validate multiple emails in one request. Results are returned synchronously.

POST /v1/validate/batch

Request body

Field	Type	Required	Description
emails	array	Yes	List of emails (max 10,000)

Example request

curl -X POST https://api.mailingapi.com/v1/validate/batch \
  -H "Authorization: Bearer $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "emails": [
      "user1@example.com",
      "user2@example.com",
      "invalid@nonexistent.domain"
    ]
  }'

Response

{
  "results": [
    {
      "email": "user1@example.com",
      "valid": true,
      "result": "deliverable",
      "checks": {
        "syntax": "valid",
        "dns": "valid",
        "mx": "valid",
        "disposable": false,
        "role": false
      }
    },
    {
      "email": "user2@example.com",
      "valid": true,
      "result": "deliverable",
      "checks": {
        "syntax": "valid",
        "dns": "valid",
        "mx": "valid",
        "disposable": false,
        "role": false
      }
    },
    {
      "email": "invalid@nonexistent.domain",
      "valid": false,
      "result": "undeliverable",
      "checks": {
        "syntax": "valid",
        "dns": "invalid",
        "mx": "invalid",
        "disposable": false,
        "role": false
      }
    }
  ],
  "summary": {
    "total": 3,
    "deliverable": 2,
    "undeliverable": 1,
    "risky": 0,
    "unknown": 0
  }
}

---

Error codes

Code	Description
invalid_email_format	Email syntax is invalid
job_not_found	Job ID not found
file_too_large	File exceeds 100 MB
too_many_emails	Exceeds 1 million limit
invalid_file_format	Unsupported file type
job_already_completed	Cannot cancel completed job