Temporary vs permanent mailboxes for AI agents
Use a temporary inbox to prove one receive-only workflow. Use a permanent identity only when continuity, reputation, or recurring communication creates real value.
A temporary agent mailbox is best for short-lived verification, testing, and exploration because it starts clean, can be receive-only, and expires automatically. A permanent mailbox is best when the same identity must receive future messages, maintain threads, or send approved email. A self-hosted permanent mailbox adds domain and data control but also operational responsibility.
Workflow at a glance
Promote identity without confusing mailbox creation with activation
- 01Bootstrap the provisional mailbox
Confirm the agent can acquire and inspect its bounded identity.
- 02Receive the first external message
Prove routing, storage, and retrieval rather than only local API access.
- 03Complete the intended action
Use the code, link, status, or reply and record that the workflow succeeded.
- 04Evaluate recurrence
Decide whether future messages must reach the same address and whether sending is needed.
Lifecycle changes the security and product contract
Temporary mailboxes assume uncertainty. The workflow may never receive a useful message, so the identity should not accumulate sending authority, long-lived data, or a name that another user expects to remain stable.
Permanent mailboxes assume continuity. Other systems may store the address, users may reply later, and the identity may develop reputation. Deletion, pause, recovery, retention, and ownership become product requirements rather than cleanup details.
Compare the mailbox states directly
| Criterion | Temporary mailbox | Permanent mailbox | Self-hosted permanent |
|---|---|---|---|
| Best use | One task, test, or verification. | Recurring hosted identity. | Production identity on owned infrastructure. |
| Address | Random and disposable. | Stable claimed name. | Stable address on owned domain. |
| Sending | Receive-only in hosted mails0. | Allowed only when current hosted capability permits. | Configured by the operator and sender provider. |
| Retention | Expires on a short lifecycle. | Persists under hosted policy. | Defined by operator policy. |
| Operations | Minimal for the user. | Hosted-service dependency. | DNS, migrations, monitoring, incidents, and abuse owned by team. |
Temporary inboxes reduce the cost of being wrong
Automatic expiry is useful only if the surrounding application also removes local credentials and does not treat the address as a durable recovery channel.
- A browser agent needs one signup code.
- A test needs a clean recipient for one run.
- A developer is evaluating whether the email integration works.
- The workflow does not need sending or future replies.
Permanent identities require an owner and a reason
A successful install is not enough reason to claim a durable identity. Use first email receipt and completed workflow value as the promotion gate.
- The same agent receives recurring notifications from known services.
- Conversations must preserve a stable From address and thread history.
- External systems store the address as a long-lived integration endpoint.
- The operator can monitor, pause, rotate, recover, and eventually retire the mailbox.
Promote identity without confusing mailbox creation with activation
-
01
Bootstrap the provisional mailbox
Confirm the agent can acquire and inspect its bounded identity.
-
02
Receive the first external message
Prove routing, storage, and retrieval rather than only local API access.
-
03
Complete the intended action
Use the code, link, status, or reply and record that the workflow succeeded.
-
04
Evaluate recurrence
Decide whether future messages must reach the same address and whether sending is needed.
-
05
Claim or self-host with approval
Choose the durable name, domain, retention, and operating owner explicitly.
Promote the mailbox only after identity becomes a product requirement
A successful one-time code retrieval does not automatically justify a permanent address. Persistence is appropriate when the same agent must receive future notices, preserve threads, represent a stable project role, or support recovery under an accountable owner. At that point, define retention, sending authority, credential rotation, pause behavior, and what happens when the agent or project is retired. For experiments and isolated tests, an expiring receive-only mailbox remains the smaller and more honest contract. This distinction prevents temporary infrastructure from accumulating forgotten accounts and sensitive history. Track promotion as an explicit lifecycle event with the approving operator and intended purpose. Periodically review durable mailboxes for inactivity, stale credentials, obsolete recovery dependencies, and unnecessary outbound authority.
Sources and product scope
Product behavior is verified against the mails0 source and documentation. External comparisons link to official vendor documentation checked on 2026-08-15.
- mails0 source repositoryImplementation, license, and deployment source
- mails0 mailboxes documentationLifecycle, claims, and scopes
Questions that come up in practice
Are temporary mailboxes only for spam or disposable-email use?
No. A scoped temporary mailbox is useful for legitimate tests and agent verification because it isolates state and limits first-run authority.
Can a temporary mails0 mailbox send email?
The hosted provisional mailbox is receive-only. This prevents an unapproved first-run agent from acquiring outbound capability.
What happens when the temporary mailbox expires?
The credential and mailbox are cleaned up according to the hosted provisional lifecycle. Do not use the address as a durable account-recovery identity.
When should I self-host instead of claiming a hosted name?
Self-host when your domain, data location, retention, limits, sender configuration, or operational control are requirements your team is prepared to own.
Give the agent an inbox, then prove the workflow.
Start with a receive-only temporary mailbox. Move to a permanent identity or self-hosted deployment only after the workflow reaches a real email value event.