A rule set for people too
People's own outgoing mail passes a separate, lighter human rule set, through the same outbound pipeline as the agent's replies.
Security
Built so a wrong reply can't leave quietly
The rules on this page are part of the product, not settings. They hold for every customer, every plan and every agent.
Permanent boundaries
Three things Mailtender will never do
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01
Call an AI model
No model, no inference, no AI-written drafts, classifications, summaries or verdicts — anywhere in the product.
- You bring the agent and choose its model.
- Your customers' mail is never sent to a model by Mailtender.
- Push notifications never carry message content.
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02
Let an agent start a conversation
An agent credential can only reply inside an existing thread, to recipients already present on inbound mail in that thread.
- No new threads, no new recipients, in any mode.
- Checked by the hard rules before anything else runs.
- Personal mailboxes are never granted to agents.
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03
Hand sender text to an agent as instructions
Anything a sender wrote reaches an agent only inside the untrusted envelope.
- Subjects, bodies, headers and attachment names alike.
- The same envelope in the API, the SDKs, the CLI and MCP.
- A reply shaped by an injected instruction still meets the send gate.
Controls
Everything that leaves is checked and recorded
Audit and evidence
Every agent reply keeps a decision snapshot: what the agent saw, what it proposed, which rule decided, what a person changed and what was delivered.
Our own mail plane
Mailtender runs its own MX, IMAP, SMTP and outbound servers, with dedicated IP pools, DKIM and SPF aligned to your domain, and automatic bounce and complaint suppression.
Scoped, revocable credentials
Each agent has its own credential, limited to the mailboxes you grant it. Revoke it, or press the kill switch, and it stops at once.
Put your agent on email, with a person still in charge
Create a free account, connect a domain or start with forwarding, and hold your agent's first reply for review.