00 / InboxFox
Available now · Version 2.1.0
Test your emails
on your Mac
Point your app at InboxFox's local SMTP server and inspect every test email on your Mac. Check the layout, links, headers, and attachments without sending mail to real inboxes. Pro also lets your tests and coding agents read the messages.
InboxFox — overview
01 / Features
Catch the email.
Check what arrived.
See what your app actually sent, from the rendered message to its headers and attachments.
A local SMTP server
Set your app's SMTP host to 127.0.0.1 and port to 1025. InboxFox catches the messages instead of delivering them to real recipients.
Messages appear as they arrive
Keep InboxFox open while testing signup, password resets, or notifications. Each message appears in the inbox as soon as it arrives.
Inspect the full message
Switch between HTML, plain text, headers, and raw email source. Check how the layout looks at phone width too.
Preview attachments
See which files your app attached and open them with Quick Look to check their contents.
Check common email problems
Review warnings about compatibility, accessibility, and delivery-related issues. Use them to spot problems before sending through your real mail service.
Connect automated tests
Use the Mailpit-compatible HTTP API to read, search, and clear captured mail from your tests. Available during the trial and with Pro.
Let your coding agent read mail
Connect through the built-in MCP server to find messages, extract links, or wait for an email to arrive. Available during the trial and with Pro.
Organize messages with tags
Label messages in the app or through the API. Group mail from a test run so you can find it and clean up afterwards.
Separate inboxes for each project
Use a different SMTP username for each project or test account, and InboxFox sorts the messages into separate inboxes. Available during the trial and with Pro.
0x / Gallery
See InboxFox in action
Read captured messages, check their layout, and connect an automated email test.
02 / AI Agents
Test an email flow
with your coding agent
Connect your agent to InboxFox through MCP, or use the Mailpit-compatible HTTP API from your tests. Read captured mail, check links and attachments, and wait for a message to arrive. Included in the trial and Pro.
Waiting for mail
Wait for the message you need
A password-reset test needs to know whether the right email arrived. Repeatedly checking the inbox adds delays and can miss a slow delivery.
Ask InboxFox to wait for a message matching your search. It returns when a match arrives or the timeout ends.
The same operation is available over HTTP at /api/v1/wait for scripts and test runners.
sleep and poll repeated checks
- sleep 5
- check the inbox nothing yet
- sleep 5
- check the inbox
wait_for_message waits for a match
- wait_for_message returns when a match arrives
Setup
Enable the API in Settings, then connect your agent. It listens on your Mac by default.
01 Install InboxFox
brew install --cask skulkworks/tap/inboxfox
Or use the download below. Launch InboxFox to start the SMTP server on 127.0.0.1:1025.
02 Turn on the API
Settings ▸ HTTP API
Included in the trial and Pro. The default API port is 8025.
03 Connect your agent
claude mcp add --transport http inboxfox http://127.0.0.1:8025/mcp
The MCP server is part of InboxFox and uses the same port as the HTTP API.
For existing Mailpit tests, update the base URL and check the compatibility notes in the API documentation. Settings includes a ready-made connection command, with your token if needed.
HTTP API
Use it from your tests
Read messages, inspect attachments, and prepare the inbox for the next run through the HTTP API.
Read the newest message
Get the newest captured message, without needing its ID first.
Search for a message
Search by recipient, sender, subject, read state, attachments, size, or date. Combine filters to find the message a test expects.
Check an attachment
Fetch an attachment and verify its contents, rather than only checking that a file was attached.
Clear captured mail
Delete selected messages, search results, or all captured mail before the next test run.
Add test messages
Add a test message over HTTP, including attachments and inline images. InboxFox stores it locally without relaying it.
Over MCP
Read and check mail through MCP
InboxFox includes seventeen MCP tools. Here are some common operations.
wait_for_message
Wait for a message matching a search, with a timeout. Return the message when it arrives or report that no match arrived in time.
get_latest_message
Read the newest message, optionally from a specific inbox.
extract_links
Get the links in a message to test confirmation or password-reset flows.
search_messages
Find messages using the same search filters as the HTTP API.
get_attachment
Read an attached file by its MIME part.
check_message
Run the app's email quality checks and get the results as structured data. Outbound link checking only runs when requested.
set_tags
Tag messages from a test run so you can find them and clean up afterwards.
send_message
Add a local test message without sending it through SMTP.
Example requests
Use these when testing signup, password resets, or generated emails.
“Trigger a password reset and check that the email arrived.”
The agent waits for the reset email, then checks the recipient, subject, and link. It reports if no matching email arrives before the timeout.
via wait_for_message
“Get the confirmation link out of the last email and follow it.”
InboxFox returns the message's links and their text so the agent can identify the confirmation URL.
via extract_links
“Clear the inbox before this run.”
The agent clears captured messages so the next run starts with an empty inbox.
via delete_messages
“Is anything wrong with the invoice email we just generated?”
The agent reads the quality-check results, including warnings about missing alt text, unsubscribe links, or dark-mode support.
via check_message
Read the API routes, search filters, MCP tools, and Mailpit compatibility notes.
Read the API documentation0x / Pricing
One price, no subscription
Try every feature free for 14 days. Afterwards, keep capturing unlimited mail in one local inbox. Pro adds separate inboxes, custom server settings, the HTTP API, and MCP for $9.99 once.
§ / Mac App Store
Bought InboxFox on the Mac App Store?
Your existing Pro purchase carries over. Leave the App Store copy installed and open the new app from its disk image first. It checks your purchase and unlocks Pro, then you can move it to Applications.
Keep your App Store copy until Pro is unlocked
Replacing the App Store app too early removes the purchase receipt needed to unlock Pro. Run the new app from the disk image first, then let it move to Applications.
- 01 Leave the App Store copy installed
- 02 Launch the new app from the downloaded disk image
- 03 It checks your App Store purchase and unlocks Pro
- 04 Let the app move itself to Applications
03 / FAQ
Frequently asked questions
SMTP setup, automated tests, and pricing.
Set your app's SMTP host to 127.0.0.1 and its port to 1025. Authentication is optional. If you supply a username, Pro can use it to choose an inbox. Passwords are ignored because InboxFox is a test server.
InboxFox stores captured messages locally and does not relay or forward them. There is no cloud inbox or account. Update checks and license activation use the internet.
You can read rendered HTML, plain text, full headers, and raw email source, preview attachments, and check the layout at phone width. The checks view flags common compatibility, accessibility, and delivery-related issues.
Every feature is available for 14 days, with no account or credit card required. Afterwards, InboxFox keeps capturing unlimited mail for free in one inbox. Buy Pro if you need the extra server and automation features.
Pro adds separate inboxes per SMTP username, a custom SMTP bind address and port, and the HTTP API and MCP server. Custom binding lets containers, virtual machines, or other devices connect to your test server. A license costs $9.99 once and covers three Macs.
Yes. Enable the HTTP API in Settings, then connect your agent to the MCP endpoint. It can read and search mail, extract links, inspect attachments, and check messages. The API and MCP are included in the trial and Pro.
No. Use wait_for_message over MCP, or /api/v1/wait over HTTP, to wait for mail matching your search. InboxFox returns when a match arrives or the timeout ends.
The API is off by default and listens on 127.0.0.1 when enabled. Its bind address is separate from SMTP. Binding the API to another address requires an access token, which InboxFox can generate.
InboxFox offers a native Mac interface, email quality checks, and a built-in MCP server. Its HTTP API is compatible with Mailpit for common test workflows. The API documentation lists the differences to check when moving existing tests.
No. Leave your App Store copy installed, open the downloaded disk image, and run InboxFox from it before moving it to Applications. It reads your App Store purchase and unlocks Pro. You can request a permanent license key in the app for your other Macs.
The direct download checks for updates and installs them through the app. Homebrew users can update through Homebrew. The Mac App Store build receives updates through the App Store.
macOS 14 Sonoma or later, on Apple silicon or Intel.
04 / Download
Check the next email your app sends
Download InboxFox, set your SMTP host to 127.0.0.1 and port to 1025, then send a test message from your app.
brew install --cask skulkworks/tap/inboxfox
Version 2.1.0 · Apple silicon and Intel · macOS 14 or later · 14-day Pro trial, then a free version. · Changelog
05 / Contact
Get in touch
Have a question or a feature idea? Send a message below. For a bug report, include your macOS version, InboxFox version, and the steps that caused the problem.