Inboxes

An inbox is one email address. Create as many as your plan allows: one per agent, per task or per customer.

const inbox = await send0.inboxes.create({
  name: "procurement-agent",          // → procurement-agent@send0.email
  display_name: "Procurement Agent",   // sender name recipients see
  send_policy: "reply_only",           // open | reply_only | approval
  retention_days: 7,                   // keep message content 1–30 days
  metadata: { team: "ops", run: 42 },  // your own labels, up to 20 keys
});

AddressesCopy Anchor Link

• Addresses are case-insensitive: Research-Agent@ and research-agent@ are the same inbox.
• Plus-addressing: mail to procurement-agent+po4471@send0.email lands in procurement-agent with tag: "po4471". Use it to tell tasks apart without creating inboxes.
• Reserved names can't be used: postmaster, abuse, admin, support, noreply, security, billing and similar.
• Mail to an address that doesn't exist is refused while the sender's server is still connected (550 5.1.1), so senders get an immediate, clear bounce.

Send policiesCopy Anchor Link

Change it any time:

await send0.inboxes.update(inbox.id, { send_policy: "approval" });

RetentionCopy Anchor Link

Each inbox keeps message content for retention_days: 7 by default, at most 30. After that the message expires:

• Its text, html, extracted_text, extracted and attachments are deleted, along with the original .eml.
• The message stays in lists, threads and search by subject, with "expired": true. Its addresses, subject, status and timestamps are kept, so reply-only sending, threading and delivery history keep working.
• GET /v1/messages/{id}/raw and forwarding it answer 410 message_expired. You can still reply to it.

35 days after it arrived or was sent, the message is deleted entirely, and a thread with no messages left goes with it. Webhook events and delivery logs are kept for 35 days too.

await send0.inboxes.update(inbox.id, { retention_days: 30 });

Save anything you need longer, such as an attachment or a code, when it arrives: a webhook or wait is the place to do it.

DeletingCopy Anchor Link

await send0.inboxes.delete(inbox.id); // needs an admin key

Mail to a deleted inbox is refused from then on. The address is never given to anyone else, so a deleted agent's mail can't land with a stranger.

LimitsCopy Anchor Link

The free plan includes 5 inboxes. Deleted inboxes don't count. Creating one more returns 402 plan_limit_reached.