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Auth Keys
Mailbox Auth Keys: Create and Use Securely
Understand what mailbox auth keys are, why they exist, and how to manage them safely for least-privilege sending access.
Audience: All customersTime: 10-15 minutes
Updated April 2026
Before you begin
- At least one active mailbox
Table of contents
1) What an auth key is
An auth key is a mailbox-scoped credential used by external tools to authenticate SMTP sends.
- Auth keys prove sending permission for one mailbox identity.
- They replace broad workspace-level credentials and reduce blast radius.
- A key can be revoked without disabling the whole workspace or all senders.
- You can issue different keys for different tools while keeping the same mailbox identity.
2) When to create separate keys
Use separate keys to improve control and incident response.
- Create one key per tool or integration (for example, CRM, sequencer, internal app).
- Avoid sharing a single key across unrelated systems.
- If one integration is compromised, you can revoke only that key.
- Use naming conventions that include system and owner for faster audits.
3) Generate a mailbox auth key
Each key should map to a clear mailbox use case.
- Open Mailboxes, select a mailbox, and click Create Auth Key.
- Use descriptive key names such as Outreach Primary or CRM Mailbox Key.
- Copy key immediately after creation.
- Store key securely in your sending tool or secret manager.
- Repeat per mailbox when different senders need isolated credentials.
4) Manage keys
Use mailbox key controls to keep access clean and secure.
- Disable keys that are no longer needed.
- Delete unused keys to reduce risk.
- Review key names and remove unknown entries per mailbox.
- Rotate keys periodically for better security hygiene.
5) SMTP connection details
Use these values in your external sending client.
- Host should match your configured SMTP hostname.
- Port is typically 587 with secure connection settings as documented in app setup guides.
- Username is your mailbox address.
- Password is your mailbox auth key.