Overview

The mailX API gives you free, programmatic access to all email deliverability and DNS tools. Every endpoint accepts a JSON body and returns a JSON response. No API key, no signup.

All tool endpoints follow the same pattern:

POST https://tools.themailx.com/api/v1/{endpoint}
Content-Type: application/json

{
  "field_name": "value"
}

Authentication

None required. All endpoints are open and free.

DNS & Authentication Checkers

SPF spf-check

Check if a domain has a valid SPF (Sender Policy Framework) DNS record. SPF specifies which mail servers are authorized to send email on behalf of a domain.

curl -X POST https://tools.themailx.com/api/v1/spf-check \
  -H "Content-Type: application/json" \
  -d '{
    "domain_name": "example.com"
}'

DKIM dkim-check

Check if a domain has a valid DKIM (DomainKeys Identified Mail) DNS record for a given selector. DKIM allows the receiver to verify that an email was sent by the domain owner.

curl -X POST https://tools.themailx.com/api/v1/dkim-check \
  -H "Content-Type: application/json" \
  -d '{
    "domain_name": "example.com",
    "dkim_selector": "google"
}'

DMARC dmarc-check

Check if a domain has a valid DMARC (Domain-based Message Authentication, Reporting & Conformance) DNS record. DMARC tells receiving servers what to do with emails that fail SPF or DKIM checks.

curl -X POST https://tools.themailx.com/api/v1/dmarc-check \
  -H "Content-Type: application/json" \
  -d '{
    "domain_name": "example.com"
}'

BIMI bimi-check

Check if a domain has a valid BIMI (Brand Indicators for Message Identification) DNS record. BIMI allows brands to display their logo next to authenticated emails in supporting email clients.

curl -X POST https://tools.themailx.com/api/v1/bimi-check \
  -H "Content-Type: application/json" \
  -d '{
    "domain_name": "example.com"
}'

Deliverability Tools

SMTP Checker smtp-check

Test an SMTP server connection by attempting to connect and authenticate. Optionally sends a test email to verify full sending capability.

curl -X POST https://tools.themailx.com/api/v1/smtp-check \
  -H "Content-Type: application/json" \
  -d '{
    "host": "smtp.gmail.com",
    "port": "587",
    "username": "user@gmail.com",
    "password": "app-password",
    "encryption": "tls",
    "from_email": "value",
    "to_email": "value"
}'

IMAP Checker imap-check

Test an IMAP server connection by attempting to connect and authenticate. Use this to verify email receiving configuration.

curl -X POST https://tools.themailx.com/api/v1/imap-check \
  -H "Content-Type: application/json" \
  -d '{
    "imap_host": "imap.gmail.com",
    "imap_port": "993",
    "username": "user@gmail.com",
    "password": "app-password",
    "imap_encryption": "tls"
}'

Blacklist Checker blacklist-check

Check if a domain or IP address is listed in popular email blacklists (DNSBLs). Being blacklisted can severely impact email deliverability.

curl -X POST https://tools.themailx.com/api/v1/blacklist-check \
  -H "Content-Type: application/json" \
  -d '{
    "domain_name": "example.com"
}'

Generators

DMARC Generator dmarc-generate

Generate a DMARC DNS record for a domain. Returns the record name, value, and type ready to be added to DNS.

curl -X POST https://tools.themailx.com/api/v1/dmarc-generate \
  -H "Content-Type: application/json" \
  -d '{
    "domain_name": "example.com",
    "email": "admin@example.com",
    "dmarc_policy": "quarantine"
}'

SPF Generator spf-generate

Generate an SPF DNS record for a domain based on the email provider being used. Returns the record name, value, and type ready to be added to DNS.

curl -X POST https://tools.themailx.com/api/v1/spf-generate \
  -H "Content-Type: application/json" \
  -d '{
    "domain_name": "example.com",
    "provider": "Google Workspace",
    "hard_fail_boolean": true
}'

BIMI Host bimi-host

Host and serve your BIMI SVG file for email authentication

curl -X POST https://tools.themailx.com/api/v1/bimi-host \
  -H "Content-Type: application/json" \
  -d '{
    "domain_name": "example.com",
    "bimi_file": "https://example.com/logo.svg"
}'

Server Finders

SMTP Finder smtp-finder

Look up SMTP server settings (host, port, encryption) for a given email provider. Use this to find the correct SMTP configuration for services like Gmail, Outlook, SendGrid, etc.

curl -X POST https://tools.themailx.com/api/v1/smtp-finder \
  -H "Content-Type: application/json" \
  -d '{
    "provider_name": "Google Workspace"
}'

IMAP Finder imap-finder

Look up IMAP server settings (host, port, encryption) for a given email provider. Use this to find the correct IMAP configuration for services like Gmail, Outlook, Yahoo, etc.

curl -X POST https://tools.themailx.com/api/v1/imap-finder \
  -H "Content-Type: application/json" \
  -d '{
    "imap_provider_name": "Google Workspace"
}'

Combined Test

Run multiple tools at once against a domain. Returns individual results for each tool.

curl -X POST https://tools.themailx.com/api/v1/combine \
  -H "Content-Type: application/json" \
  -d '{
    "inputs": {
      "domain_name": "google.com"
    },
    "tools": ["spf-check", "dmarc-check", "bimi-check", "blacklist-check"]
  }'

Error Handling

All endpoints return standard HTTP status codes:

Validation errors return a structured response:

{
  "messages": {
    "domain_name": ["The domain name field is required."]
  }
}