It always happens the same way. You build an AI agent that reads and sends email through your personal Gmail. You point it at five test accounts, everything works. You turn it loose on a hundred parallel tasks. Twelve hours later your app password stops working, your OAuth token is invalidated, and you're staring at a "suspicious activity" page.

Triage: the next hour

  1. Check Gmail's "Last account activity" page. mail.google.com/mail/u/0/#settings/general → "Details". Look for IPs and timestamps.
  2. Do not immediately re-auth. Wait 24 hours. Rotate the OAuth client ID.
  3. Re-verify from a clean browser on a residential IP.
  4. Disable the agent. Or you'll trip the flag again.
  5. Check for silently-discarded sends. Gmail rate-limits well before banning.

Why Gmail bans AI agents

Gmail's abuse detection is tuned for humans — a few checks per hour, dozens of sends per day, predictable circadian patterns. Agents do none of that. Signals that get you flagged:

  • High-frequency IMAP polling (looks like a scraper)
  • Many parallel sessions from one datacenter IP
  • Programmatic send volume — 100 sends/hour triggers alarms
  • App passwords without enforced 2FA
  • Unverified OAuth apps with sensitive scopes
  • Sudden country changes when you redeploy

These signals don't mean your agent is malicious — they mean your agent is not a human, and Gmail's ToS is that Gmail is for humans.

The four options after a ban

Harden Gmail: Workspace + verified OAuth + under 500 sends/day + residential proxies. Works at small scale.

Buy more accounts: Tempting, against ToS, accounts arrive pre-flagged.

Transactional provider for sending: Resend/SendGrid/SES solve outbound. Your agent still has no inbox.

Dedicated agent infrastructure: What Lumbox is built for. Every agent gets its own address, fully isolated.

Why dedicated inboxes don't get banned

  • One inbox per task. No shared login history to trip detection.
  • Short-lived, purpose-tagged. No lingering credentials.
  • Infrastructure designed for high-concurrency API access — the opposite of Gmail.

Migration path

The surface area that touches email is usually one or two functions:

  • get_latest_otp() → lumbox.inboxes.waitForOtp(inbox_id)
  • send_reply(to, body) → lumbox.inboxes.send(inbox_id, ...)

The agent logic stays the same. Swap the transport, not the brain. lumbox.co — no Gmail, no bans, no 3am recovery flows.