---
title: "SMTP STARTTLS and certificate check"
method: GET
path: "/email/smtp-tls"
tags: ["email"]
---

# SMTP STARTTLS and certificate check

`GET /email/smtp-tls`

## Request

- Base URL: `https://intodns.ai/api`
- URL: `https://intodns.ai/api/email/smtp-tls`
- Auth: none required

Connect to MX servers on SMTP port 25, verify STARTTLS support, TLS certificate trust, hostname match, expiry, and FCrDNS. Measured from the IntoDNS.ai server: a host that does not answer there has reachable=false and startTlsSupported=null (not measured), which is not evidence that it lacks STARTTLS.

## Query parameters

- `domain` string, required

## Response `200`

SMTP STARTTLS analysis result

- SMTPTLSResult
  - `domain` string
  - `checkedAt` string, date-time
  - `mxRecords` object[]
  - `servers` object[]
  - `summary` object
  - `issues` string[]

---

[API](https://skmtc.dev/intodns/apis/intodns-ai-api.md) · [All operations](https://skmtc.dev/intodns/apis/intodns-ai-api/llms.txt) · [OpenAPI document](https://skmtc.dev/intodns/apis/intodns-ai-api/revisions/c6c196b2fb4c?raw)