CLOUDFLARE APP OR YOUR OWN MAIL SERVERS

Box Ox vs
Postal.

Choose Box Ox for a browser mail client and app API on Cloudflare. Choose Postal when you want to run the delivery servers yourself, accept SMTP submissions, and control sending IP pools.

Compare the details ↓Which fits your team?

CHOOSE BOX OX WHEN

Your inbox is part of your app.

You want to read and reply to conversations in a browser.
You prefer Cloudflare services to operating an SMTP server.
You need built-in, scoped mailbox access for apps and agents.

CHOOSE POSTAL WHEN

You want to run the delivery servers.

You need SMTP submission and your own delivery infrastructure.
Your team can maintain servers, DNS, and sending IP reputation.
You need MIT-licensed mail-server software or IP-pool controls.

THE PRACTICAL DIFFERENCES

What changes in your day?

A closer look at features, responsibilities, and costs.

On a small screen, scroll the table sideways to compare both products.

Box Ox vs Postal: features, responsibilities, and tradeoffs
What matters to you	Box Ox	Postal
Where it runs	An application deployed on Cloudflare Workers, with D1 and R2 in your account.	Mail-delivery software you install on your own servers. [2]
Send application mail	HTTP API, JavaScript SDK, and CLI. Cloudflare Email Service delivers outgoing messages.	SMTP submission and an HTTP API, with your Postal installation handling delivery. [1]
Keep an SMTP integration	The app exposes an HTTP API, not an SMTP submission server. Sending needs the full install on Cloudflare Workers Paid.	Applications can submit mail over SMTP. [5]
Read and reply to mail	Threaded browser inbox, compose, search, and sent-mail copies. Free is receiving-only.	A delivery dashboard with message history, queues, logs, and search. It is a different workflow from a conversation inbox. [1]
Handle incoming mail	Route mail into addresses and conversations in the app, with inbound webhooks for integrations.	Route incoming mail to HTTP endpoints, other SMTP servers, or email addresses. [3]
Agent access	Built-in OAuth/MCP and a grant-limited agent API. Give agents mailbox access with revocation and sending caps.	The documented integration points include SMTP, HTTP APIs, and webhooks. Build the mailbox/agent workflow you need. [1]
Sending IP control	Uses Cloudflare’s mail transport. No Box Ox controls for owning or assigning delivery IP pools.	Configure sending IP pools and select IPs for particular senders or recipients. [6]
Infrastructure work	Maintain the installation, Cloudflare configuration, data recovery, and updates. No Postal-style SMTP host to operate.	Provision and maintain the server stack and its networking. Postal documents Docker, MariaDB, DNS, and SMTP connectivity requirements. [2]
License	Application: FSL-1.1-MIT, with competing-service restrictions. SDK and CLI: MIT. Read the terms for your use case.	MIT-licensed open-source software. [4]
What you pay for	No Box Ox subscription. Cloudflare plan and usage charges apply; sending needs Workers Paid.	The software is MIT-licensed. Budget separately for servers, storage, and operating the service. [2] [4]

Box Ox is free. On Cloudflare Workers Free it installs as an inbox. Sending, optional AI, semantic search, and browser features need Cloudflare Workers Paid. Review requirements and testing status →

WHERE BOX OX FITS

A conversation.
An app. An agent.

Send an order update from your app, read the customer’s reply in your inbox, and let an agent read the conversation with a mailbox grant. You control the installation and the permissions. Outbound mail uses Cloudflare Email Service, which Cloudflare’s terms cover for transactional sending; confirm with Cloudflare before relying on it for everyday conversational replies.

This is where Box Ox focuses. Choose Postal when operating the mail servers and controlling sending IPs are part of your requirements.

Where Postal is the better fit

Postal is the better fit when operating the mail-server layer is part of your goal. Box Ox trades that transport control for a Cloudflare-based application with an inbox and scoped agent access. Box Ox still needs an operator: self-hosting does not remove responsibility for access, backups, updates, or usage.

We have not run a head-to-head delivery or throughput benchmark. This page makes no claim that Box Ox is faster, cheaper at every volume, or more likely to reach an inbox.

BEFORE YOU SWITCH

Keep the migration practical.

Decide whether you need your own SMTP server and sending IP controls. Box Ox does not expose Postal’s delivery infrastructure controls.
Adapt SMTP or Postal API integrations to the Box Ox API. Review event payloads and signature verification separately.
Plan mailbox and message-history migration separately. There is no automatic Postal migration included in this comparison.
Verify your domain, access policies, backup plan, and mail round trip before changing production routing.