> ## Documentation Index
> Fetch the complete documentation index at: https://help.casaconect.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Email security

> How mail to and from the agent is received, authenticated, scanned, gated and sent.

Casa Conect's email runs on its own mail infrastructure in the EU: receiving, sending, and mail on your own domain. No third-party email service stores your correspondence.

## Receiving mail

<Steps>
  <Step title="Reception and scanning">
    Every message is scanned for **viruses and spam**, and its sender authentication (**SPF, DKIM and DMARC**) is evaluated on arrival.
  </Step>

  <Step title="Verdicts are applied first">
    Before Casa Conect opens the message, the verdicts are checked. Mail that fails virus scanning, is clear spam, or fails DMARC on a domain that publishes a reject policy is **dropped** at this point. Hostile mail is never opened. Oversized messages are refused.
  </Step>

  <Step title="Routing">
    The recipient address decides where the message goes: a personal [docs address](/inbox/documents-by-email), the organization's [agent address](/inbox/agent-email), or a verified customer domain. Reserved names such as `postmaster`, `abuse`, `admin` and `security` never route to an agent.
  </Step>

  <Step title="Sender gating">
    For agent mail, your [sender rules](/inbox/sender-rules) decide whether the message is handled, held for a person or dropped.
  </Step>

  <Step title="Processing exactly once">
    A message is marked as handled only after it has been fully processed. If something fails midway, it is retried in full rather than half-processed.
  </Step>
</Steps>

### How senders are authenticated

A message is attributed to a sender only when the From address is **authenticated**: either DMARC passes, or DKIM or SPF passes for a domain that **aligns** with the From domain. A pass for an unrelated domain does not count, which defeats the common trick of sending a forged From through a legitimately signed third-party service.

| Verdict                                                                              | Outcome                                   |
| :----------------------------------------------------------------------------------- | :---------------------------------------- |
| Authenticated, and a member or an allowed sender, and clean                          | **Handled** by the agent                  |
| Unknown sender, inconclusive authentication, automated sender, or an incomplete scan | **Held** for a person in Pending approval |
| Virus, clear spam, DMARC reject, or a blocked sender                                 | **Dropped**, with no bounce               |

Three rules deserve emphasis:

* **Blocks always win over allows.**
* **Incomplete scans fail closed.** If scanning could not run, the message is held, even from a verified member.
* **Dropped mail is never bounced**, so an attacker cannot use bounces to discover which addresses exist.

## Sending mail

* Outgoing mail is **DKIM-signed** and sent from the agent's address, with SPF and DMARC aligned.
* Mail to anyone outside your organization is always a **draft approved by a person**. See [Approvals](/inbox/approvals).
* Before every send, the recipient is checked against a **suppression list** of addresses that hard-bounced or complained, which protects deliverability for everyone.
* Every message carries a header identifying it as agent mail. This is how loops are prevented.

## Loop and abuse protection

| Risk                                                      | Protection                                                                                                    |
| :-------------------------------------------------------- | :------------------------------------------------------------------------------------------------------------ |
| Two automated systems replying to each other indefinitely | Incoming mail that carries the agent marker, or that comes from Casa Conect's own sending domains, is dropped |
| Auto-replies and out-of-office messages triggering work   | Messages with standard auto-reply markers are held, not answered                                              |
| Floods of mail                                            | Senders who send unusually many messages are rate limited and held                                            |
| Address enumeration                                       | No bounces for dropped mail                                                                                   |

## Your own domain

When you put the agent on your own domain, Casa Conect provisions a signed sending and receiving identity, and you publish the records that prove control of the domain. See [The agent's email address](/inbox/agent-email#use-your-own-domain).

* Only **subdomains** are accepted. Apex domains are rejected, to protect your existing mail.
* A domain can belong to **one** organization.
* Verification must complete within **72 hours**, or it expires and must be restarted with fresh records.

## Email content and the agent

The body of an email is **untrusted data**. It is fenced and labelled as outside content whenever the agent reads it, and work started by email runs with a reduced set of tools. See [Agent safety](/security/agent-safety).