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An inbox is a unique email address assigned to an agent. When you create an inbox, the agent can immediately send and receive email from that address.

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Address format

{username}@{your-subdomain}.openmail.sh
For example: jane@lobster.openmail.sh
  • If you provide a username, it becomes the local part of the address
  • If you omit it, we generate a random 8-character alphanumeric string
  • Usernames must be 3–30 characters, lowercase alphanumeric with dots and hyphens allowed

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External ID

You can attach your own identifier to an inbox via externalId. This is included in webhook payloads as external_id so you can map inbound emails back to your internal user or agent without an extra lookup.

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Limits

LimitValue
Inbox creation100/day per account
Contact us if you need higher limits.

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Lifecycle

Deleting an inbox (DELETE /v1/inboxes/:id) permanently removes the inbox and all associated messages, threads, and attachments. This is not reversible.