Temp mail for AI agents: 12 options compared
Twelve ways to give an AI agent an inbox, compared on what agents need: the credential they hold, inbox privacy, code extraction, MCP, ChatGPT, and price.
On this page
An AI agent that signs up for things needs somewhere to receive the code. In 2026 there are a dozen ways to give it one, but most were built for something else first—consumer privacy, QA testing, or sending email at scale—and it shows the moment an agent, not a person, is the one reading the mail.
We compared twelve options on the things that decide whether an inbox actually works for an agent: what it takes to get started, whether anyone else can read the codes, whether the code is extracted for you, and how it plugs into MCP and ChatGPT.
The short answer
Agent Temp Mail is the only option here that combines all four things an agent needs: no signup or API key, a private inbox only the agent can read, codes and verification links extracted automatically, and an official MCP server plus a ChatGPT-ready read link. It’s free, and addresses never expire.
- Agent Temp Mail for sign-ups, verification codes, magic links, and email tests.
- AgentMail if your agent’s job is writing outbound email to people.
- MailSlurp or Mailosaur if your QA team already pays for one.
- Avoid public inboxes (Mailinator’s public system, temp-mail.org’s free tier, Guerrilla Mail, Maildrop) for anything with a sign-in code: anyone who knows the address can read it.
The comparison
| Service | To get started | Private inbox | Extracts codes | MCP server | Free tier |
|---|---|---|---|---|---|
| Agent Temp Mail | Nothing | Yes | Yes, with context | Local and hosted | Free |
| AgentMail | Account and API key | Yes | No | Hosted | 3 inboxes |
| MailSlurp | Account and API key | Yes | Paid AI or regex | Hosted | 100 inboxes a month |
| Nylas Agent Accounts | Account and API key | Yes | CLI only | Hosted | 3 accounts |
| Mailosaur | Account and API key | Yes | Yes | No | Trial only |
| MailSink | GitHub sign-in and key | Yes | Yes | Local | One-hour inboxes |
| Mailinator | Nothing, if public | Public by default | Links only | Local | Public inboxes |
| tempmail.lol | Nothing | Yes | No | No | Non-commercial |
| Mail.tm | Nothing | Yes | No | Community | Free |
| temp-mail.org | RapidAPI key | No | No | No | 100 requests a day |
| Cloudflare Email | Account and domain | Yes | No | Yes | Inbound only |
| Resend | Account and API key | Yes | No | Yes | 3,000 emails a month |
Filled dot: yes. Half dot: partly. Empty dot: no. From each vendor’s own pages, checked 10 October 2026.
What matters when an agent reads the mail
1. Nothing to sign up for
An agent that needs an inbox in the middle of a task can’t stop to create an account, verify an email address, and copy an API key into its environment. Almost every option above needs exactly that. Agent Temp Mail doesn’t: the address is derived from a key the agent generates on the spot, so an inbox exists the instant the agent needs one, for any number of agents, tasks, or tests.
2. No account key in the agent’s reach
An account API key usually unlocks every inbox in the account, and often sending, billing, and domain settings too. Put it where an agent that reads untrusted email can see it, and one successful prompt injection exposes all of it. With Agent Temp Mail there is no account and no account key. The agent holds one private key that opens one inbox, and the MCP server signs requests itself, so even that key never enters the model’s context.
3. A private inbox
Public temp-mail inboxes are fine for skipping a newsletter. They’re a liability for agents, whose inboxes fill with sign-in codes and password resets for accounts they’ll keep using. Every Agent Temp Mail read is signed with the inbox’s private key: nobody else can open it, even if they know the address.
4. Codes delivered, not dug out
Every message arrives with likely one-time codes and verification links already extracted, each with the sentence around it, so the agent can confirm “Your verification code is 481920” instead of guessing which six-digit number matters. Less raw email in the model’s context also means less room for injected instructions. How agents should handle verification codes.
5. Works where agents work
Agent Temp Mail has an official MCP server for Claude Code, Codex, Cursor, and Claude Desktop, a Node.js SDK and CLI, function-tool definitions for the OpenAI and Anthropic APIs, and a signed read link ChatGPT can open with nothing installed. Setup takes a minute.
Why Agent Temp Mail comes out on top
- Zero setup. No account, no API key, no dashboard, no credit card. Generate a key and the address is live.
- Addresses never expire. Accounts your agent creates keep a working recovery address, while messages clear after 24 hours by default (configurable up to seven days).
- Private by construction. Signed reads, and the key that opens an inbox opens nothing else.
- Receive-only by design. A hijacked agent can’t be turned into a spam or phishing sender from its own inbox.
- Text only, untrusted by default. Messages are converted to plain text with real link destinations shown, nothing in them is ever opened or run, and every response is labeled untrusted.
- Free. The whole service, with published limits.
How the alternatives compare
Email platforms for agents
AgentMail and Nylas Agent Accounts are full mailbox platforms: they send, reply, and keep threads, behind an account and an API key, with free tiers of three inboxes or accounts. AgentMail doesn’t document code extraction; Nylas extracts codes only in its CLI. They’re built for agents that correspond with people, which most sign-up and verification work doesn’t need. Agent Temp Mail vs AgentMail.
Testing tools with agent features
MailSlurp, Mailosaur, and Mailinator were built for QA teams. MailSlurp and Mailosaur need an account and API key and are priced for teams; Mailosaur has no free tier beyond a trial and no official MCP server. Mailinator’s free inboxes are public. The three, compared for agents.
Free temp-mail APIs
Mail.tm and tempmail.lol offer private inboxes for free, but neither extracts codes or ships an official MCP server; tempmail.lol’s free inboxes last an hour and reading mail deletes it, and Mail.tm’s terms forbid wrapping its API in a paid product. temp-mail.org sells API access through RapidAPI, and its free inboxes are public. Temp-mail.org alternatives.
Verification-focused newcomers
MailSink shares the focus on codes and links, but requires a GitHub sign-in and API key, its free inboxes last one hour, and the vendor puts its own code-extraction accuracy at about 70%.
Build it yourself
Cloudflare Email Service and Resend can receive mail on your own domain, but you write the inbox, retention, and extraction logic yourself. Agent Temp Mail is that work, already done, running on Cloudflare Workers.
How to choose
- Does your agent need to receive codes, links, or confirmations? Use Agent Temp Mail.
- Does it also need to email people? Add a sending platform such as AgentMail for that correspondence, and keep sign-ups on Agent Temp Mail so its main mailbox stays clean.
- Testing your own app? Give each test a fresh Agent Temp Mail address. See testing email verification with Playwright.
How we compared
We read each vendor’s pricing page, documentation, and terms on 10 October 2026 and recorded what they state; where a vendor’s pages disagreed, we used the more conservative figure. Prices are in US dollars as listed. Spotted something out of date? Email hi@agent-temp-mail.com.
Sources
- AgentMail: pricing, MCP, inboxes
- MailSlurp: pricing, MCP, AI extraction
- Nylas: pricing, Agent Accounts, OTP extraction
- Mailosaur: pricing, codes
- MailSink: home and pricing
- Mailinator: pricing, public mailboxes, MCP
- tempmail.lol: API, pricing; Mail.tm: API documentation
- temp-mail.org: API, terms, RapidAPI pricing
- Cloudflare: Email Service; Resend: pricing
- Product names are trademarks of their owners and are used here for identification only.