Unitpost

Probe-verified · tier 2 · checked 26 Sep 2026

Email platform for developers to send transactional and marketing emails, manage contacts, segments, templates, domains, inbound email, webhooks, and suppressions via REST API, SDKs, SMTP relay, or MCP server. Includes email design suite and AI assistant UnitAI.

email and messagingdeveloper platforms also inemail-messagingdeveloper-platforms

What we tested

Probed live on 26 Sep 2026 against rubric v1.2. 2 of 5 checks passed. 2 unknown.

PROBE-VERIFIEDtier 2 of 3

?Markdown negotiationAccept: text/markdown · unknown

?Markdown twin at a predictable URL/page.md · unknown

✓llms.txt/llms.txt

✓API catalogRFC 9727

—MCP endpoint answers tools/listinitialize → tools/list, no credentials

✓MCP server card

/.well-known/mcp/server-card.json · present; could not ask whether its server answers

not scored

—Platform-supplied

not applicable — no MCP endpoint answered

not scored

✓Other agent files at well-known paths

agent-skills/index.json · oauth-authorization-server · oauth-protected-resource · http-message-signatures-directory · found: Agent Skills index

not scored

Context

118 sites in the index share the category email and messaging. 25 transactional sites share it.

How we grade

Three tiers. Every listing shows which one it has reached, and when. The rubric.

tier 1

Declared

The site says agents are welcome in its robots.txt. A permission, not a capability.

✓

tier 2

Probe-verified

We fetched the site and tested each signal ourselves. Dated, repeatable, re-checked on a schedule.

this site · 26 Sep 2026

tier 3

Behaviourally verified

An agent completed the action end to end — booked, bought, submitted — and it worked.

coming

Own this site?

1 check did not pass when we last looked: MCP endpoint answers tools/list. Each is a small, specific fix; the rubric says exactly what we look for.

Behavioural verification — an agent completing your key actions end to end, with the date published here — opens to a small founding cohort first. Leave an email to be in it.

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CMDK

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Instantly API Docs

API documentation for Instantly's email outreach platform, enabling programmatic management of email campaigns, leads, accounts, analytics, webhooks, and workspace operations via API v2.

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lemlist Developer Docs

API documentation for lemlist to integrate and automate email outreach, including managing campaigns, leads, teams, and email accounts.

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Notocat Developer Docs

Documentation for Notocat, a Notion-to-newsletter tool offering API integration, contact syncing, email campaign creation from Notion pages, and custom CSS styling for newsletters.

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Benchmark Email API

API for programmatic management of email contacts, campaigns, reports, and domains, including contact and list management, campaign creation, and analytics access via REST API.

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DeBounce API

DeBounce API provides email validation services including real-time validation, bulk email list processing, contact data enrichment, disposable email detection, and company logo lookup via API endpoints.

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Record generated from a live database query. Method: about the index.

How we found this site: probe discovery. This site didn’t declare agent access — we found it by checking the open web. Everything above was tested the same way, against the same rubric, on the date shown. How we choose what to check, and how to opt out →

Where this sits

More business email and messaging developer platforms (also in) Browse the index How we grade