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://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

Use this when the user asks whether a domain's SPF record is valid, which servers may send email for a domain, or why SPF fails. Returns the live SPF record, a pass/fail status and a fix suggestion.

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

DKIM dkim-check

Use this when the user wants to verify DKIM for a domain. Pass the DKIM selector if known (for example google for Google Workspace, selector1 or selector2 for Microsoft 365). If the selector is unknown, omit it: mailX then tries common selectors and returns the ones it finds. Returns the published key and its status. A miss on common selectors does not prove DKIM is absent.

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

DMARC dmarc-check

Use this when the user asks about DMARC, spoofing protection, or what happens to emails that fail authentication. Returns the live DMARC record, its policy and a fix suggestion.

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

BIMI bimi-check

Use this when the user asks about BIMI or showing a brand logo next to their emails in inboxes. Returns the live BIMI record, the logo URL it declares, and a fix suggestion.

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

Deliverability Tools

SMTP Checker smtp-check

Use this only when the user explicitly asks to test an SMTP login for a mail account they control and provides its credentials. Connects to the SMTP server and reports whether connection, encryption and authentication succeed. If from_email and to_email are both given, it also sends one test email. Credentials are not stored.

curl -X POST https://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

Use this only when the user explicitly asks to test an IMAP login for a mailbox they control and provides its credentials. Connects to the IMAP server and reports whether connection, encryption and authentication succeed. Credentials are not stored.

curl -X POST https://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

Use this when the user suspects their domain is blacklisted or blocked. Checks the domain against major DNS blocklists and returns the result for each list.

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

Generators

DMARC Generator dmarc-generate

Use this when the user needs a DMARC record. Returns the record name, value and type ready to publish. mailX does not publish it.

curl -X POST https://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

Use this when the user needs a new SPF record for their email provider. Returns a TXT record ready to publish, or explains what to set up instead when the provider does not need a root SPF include. mailX does not publish it.

curl -X POST https://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://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

Use this when the user needs the outgoing mail (SMTP) server settings for an email provider or sending service, such as Gmail, Outlook, Microsoft 365, Zoho, Amazon SES or SendGrid. Returns the host, ports with encryption, what to use to log in, and the provider's setup guide. Never asks for the user's credentials.

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

IMAP Finder imap-finder

Use this when the user needs the incoming mail (IMAP) server settings for an email provider, such as Gmail, Outlook, Yahoo, iCloud or Zoho. Returns the host, ports with encryption and the provider's setup guide. Never asks for the user's credentials.

curl -X POST https://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://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."]
  }
}