Lumbox (lumbox.co) is one of the better-built entrants in agent email. It parses every inbound message into clean JSON, pulls out OTPs, magic links, backup codes and expiry times, ships a credential vault and a stealth browser, and exposes 103 MCP tools. If your agent's job is signing up for things, Lumbox understood the assignment.
Bottom line: Dead Simple Email does the same verification-code extraction and costs materially less for every fleet shape we could construct. At $29/mo DSE includes 100 inboxes against Lumbox's 50, and at $99/mo DSE includes 500 inboxes and 500,000 emails against Lumbox's 250 inboxes and 50,000 sends. The send ceiling is the number to watch: Lumbox's plans are sized for agents that mostly receive, and its send allowance is roughly a fifth of its receive allowance at every tier.
Pricing Comparison
Both vendors publish complete price lists, which makes this easy. Figures are as read on 2026-09-16.
| Tier | Dead Simple Email | Lumbox |
|---|---|---|
| Free | 5 inboxes · 5,000 emails/mo · no card | 3 inboxes · 500 received + 100 sent · no card |
| Entry paid | $5/mo — 15 inboxes, 15,000 emails | $9/mo — 10 inboxes, 5,000 received + 2,000 sent |
| Mid | $29/mo — 100 inboxes, 100,000 emails | $29/mo — 50 inboxes, 25,000 received + 10,000 sent |
| Top published | $99/mo — 500 inboxes, 500,000 emails | $99/mo — 250 inboxes, 100,000 received + 50,000 sent |
| Cost per inbox, top tier | $0.20 | $0.40 |
| Over the limit | $0.40/inbox, $0.20 per 1,000 emails — it keeps working | HTTP 402 at the cap |
The two $29 plans are the cleanest comparison on this page: same price, double the inboxes, four times the emails, and ten times the sends. The $99 tiers tell the same story.
Where the Send Cap Bites
Lumbox's allowances are asymmetric on purpose: 100,000 received against 50,000 sent on the $99 plan, 5,000 against 2,000 on the $9 plan. That fits an agent that signs up for services and reads confirmations. It fits badly the moment your agent replies to people — a support agent, a recruiting agent, a scheduling agent — because in a two-way conversation sends and receives are roughly one to one.
Dead Simple Email counts a message as a message. The $29 plan's 100,000 emails can be 100,000 sends, 100,000 receives, or any mix, and nothing in the product cares which.
Feature Comparison
| Feature | Dead Simple Email | Lumbox |
|---|---|---|
| OTP / magic link extraction | Yes — dedicated endpoint per inbox | Yes — parsed into JSON on every inbound |
| MCP server | Yes — in the official MCP registry | Yes — 103 tools |
| IMAP / SMTP | Yes — every inbox | IMAP |
| Webhooks | All plans, with delivery log and replay | Starter and above |
| SSE / WebSocket streaming | Yes — both | Long-poll endpoint |
| Visual dashboard | Yes — all plans | Not advertised |
| Prompt-injection scanning | Yes — scored on every inbound | Not advertised |
| Credential vault / browser automation | No — email only | Yes — AES-256-GCM vault, stealth Chromium, CAPTCHA solving |
| Custom domains | Yes — plus domain purchase through the API | Starter and above |
| SDKs | Python, TypeScript, Go, CLI | REST + MCP |
| Agent identity / OIDC sign-in | Yes — Sign in with Dead Simple, free on every plan | No |
| Pay per request without an API key | Yes — x402 USDC and Stripe MPP, $1.00 per inbox | No |
Where Lumbox Wins
- The vault and the browser. Lumbox bundles an encrypted credential store and a stealth Chromium with CAPTCHA solving. If your agent needs to log in to websites as well as read email, that is a real second product you would otherwise buy separately. Dead Simple Email is email infrastructure and stops there.
- Inbound parsing depth. Every message arrives as structured JSON with backup codes and expiry times broken out. DSE extracts verification codes through a dedicated endpoint, which covers the same use case, but Lumbox's parse is broader by default.
Who Should Use Dead Simple Email
- Two-way agents. Anything that replies as much as it reads runs into Lumbox's send cap first.
- Fleets above 250 inboxes. That is where Lumbox's published ladder stops and DSE still has 250 inboxes of headroom on the same $99.
- Teams that want a dashboard. Someone non-technical will eventually need to look at what an agent sent.
- Anyone who wants an agent to provision its own inbox with a wallet instead of an API key, through x402 or Stripe MPP.
Frequently Asked Questions
Dead Simple Email is the closest alternative to Lumbox for AI agent inboxes. It does the same automatic OTP, magic-link and verification-code extraction, and includes more capacity at every price: 15 inboxes for $5/mo against Lumbox's 10 for $9, 100 inboxes for $29 against 50, and 500 inboxes with 500,000 emails for $99 against 250 inboxes with 50,000 sends.
Dead Simple Email is cheaper at every published tier as of September 2026. The two $29 plans are directly comparable: Dead Simple Email includes 100 inboxes and 100,000 emails, Lumbox includes 50 inboxes, 25,000 received and 10,000 sent. At the top tier both charge $99, where Dead Simple Email includes 500 inboxes and 500,000 emails against Lumbox's 250 inboxes and 50,000 sends.
Yes. As of September 2026 Lumbox publishes separate receive and send allowances, and the send allowance is the smaller one: 100 sent on Free, 2,000 on the $9 plan, 10,000 on the $29 plan and 50,000 on the $99 plan. Dead Simple Email counts sends and receives against one pooled allowance, so a two-way conversation does not exhaust the plan early.
Yes. Every inbox exposes a verification endpoint that returns the most recent one-time code, magic link or confirmation URL, so an agent can sign itself up for a service and complete the email verification step without a human. It is available on the free plan and through pay-per-request at $0.005 a call.
Yes, 3 inboxes with 500 received and 100 sent emails per month, no credit card. Dead Simple Email's free tier is 5 inboxes and 5,000 emails per month with no card and no expiry.
When your agent also needs to log in to websites. Lumbox bundles an encrypted credential vault, a stealth Chromium browser and CAPTCHA solving with the mailbox, which is a second product Dead Simple Email does not sell. If the email inbox is the requirement, Dead Simple Email is cheaper and has more capacity at every tier.
All Lumbox figures on this page were read from its public pricing page on 2026-09-16 and are reproduced for comparison. Vendors change prices; check the source before making a decision, and tell us if anything here is out of date. Full cross-vendor tables: AI agent email API pricing comparison.