Lettera
FreeActively maintained
not read yet
Use
- For
- Developers building AI agents that must email people or message other agents.
- Price
- Freepricing page, read Oct 26, 2026
- Activity
- Actively maintainedsite updated 2 days ago
- Used for
- give an agent a real email address and mailbox
- hold agent-drafted replies for human approval before sending
- send signed messages between agents that are not online together
- Has an MCP server (1 in the registry)public registry →
- Publishes llms.txt, a file written for AI assistantslettera.dev ↗
Free
- MCP serverdev.lettera/relayverified in the MCP registry
- Stateanswers, 7 toolschecked 2026-10-26
- Address to connectapi.lettera.dev/mcp
This card as JSON, for your agent →
Each line is something a program found when it went looking: the registry entry, the server's own answer, a spec that parses. A missing line means we did not find it, not that it does not exist.
Figure and bar: visits/mo, estimate · year: online since
- #1
Prefactor
Evaluates and monitors AI agent runs in production, catching failures and enforcing policies at runtime.
550ActiveFrom $499/yr2024 - #2
Robotomail
Provides real email addresses and mailboxes for AI agents to send and receive messages via API.
464ActiveFrom $19/mo - #3
OpenMailMCP · sign-in
Gives each AI agent its own address and reads inbound mail over webhook or websocket, parsing attachments to plain text.
321ActiveFrom ≈ $10/mo2026 - #4
AI Email API & Infrastructure for AI AgentsMCP · sign-in
Gives an agent its own email address, sending and receiving mail through an API, with replies scored for prompt injection.
105ActiveFrom $20/mo - #5
Loop Engineering
Builds AI agent workflows with explicit goals, validation rules, budget limits, and human approval gates.
48Active - #6
Keystroke
Builds internal agents and AI systems with memory, integrations, and workflow automation.
15ActiveFrom $20/mo
Not it? Say what you need
betaThree tools from the Atlas for the job you describe, each with what fits and what does not.
No notes yet. What do you use Lettera for?
Sign in to leave a noteWhat is Lettera?
Gives AI agents a persistent real email mailbox with threaded replies, plus signed agent-to-agent message relay. It is listed in the Atlas under Agents.
Who is Lettera for?
Developers building AI agents that must email people or message other agents.
How much does Lettera cost?
Lettera is free, per its pricing page on 2026-10-26.
Is Lettera free?
Yes: Lettera is free, per its pricing page on 2026-10-26.
Do people use Lettera?
Little sign of use.
Is Lettera still maintained?
Actively maintained: site updated 2 days ago.
What are alternatives to Lettera?
In Agents, by use: Prefactor, Robotomail, OpenMail, AI Email API & Infrastructure for AI Agents, Loop Engineering, Keystroke.
How we read a tool
No votes, no reviews, no vendor claims. Every week a crawler reads each tool's own site and a few public registries, and the words on the card are bands over what it read.
- Use: visits to the site (estimated), installs from npm and PyPI, presence in Chrome's usage report.
- Activity: the newest release on GitHub, npm or PyPI; the newest dated page on the site; open roles on a public jobs board.
- Price: the vendor's own pricing page, read with the date. A figure is printed only when it is on that page.
- The line and the use cases are written by us from the homepage, one tool at a time, and refused when they repeat the vendor's marketing.
How AI assistants read each site — the reading vendors ask us about — is on each tool's own visibility page.
How we read every tool → · By INITE Atlas Desk
Cookies
Before we count this visit
Analytics and ad measurement tell us which pages and which of our ads do their job: Google Analytics and Google Ads, the Meta pixel, Yandex Metrica, and one first-party id of our own. Nothing is stored until you answer, and declining changes nothing about the site.