Atlas / MCP servers / benethos-hub / mailbox

mailboxCAUTION

mcp/benethos-hub/mailbox

Self-hosted REST API and web UI for all your mailboxes (IMAP, JMAP, POP3, Gmail, Microsoft 365, Outlook.com), with a Python client and an MCP server so AI agents read, sort, draft and send mail, only within the rights, folders and send limits you grant. Change feed, signed webhooks, audit.

Verdict
CAUTION
Grade
C
Trust score
75 /100
Exposed tools
—
Transport
stdio · streamable-http
License
MIT
Stars
2
01

Overview

From the repository's own README, as read at the audited commit. Badges and raw HTML are left out.

[](https://github.com/benethos-hub/mailbox/actions/workflows/ci.yml) [](https://pypi.org/project/benethos-mailbox-service/) [](https://pypi.org/project/benethos-mailbox-mcp/) [](https://pypi.org/project/benethos-mailbox-client/) [](https://pypi.org/project/benethos-mailbox-common/) [](https://github.com/benethos-hub/mailbox/pkgs/container/benethos-mailbox-service) [](https://github.com/benethos-hub/mailbox/pkgs/container/benethos-mailbox-mcp) [](https://pypi.org/project/benethos-mailbox-service/) [](https://github.com/benethos-hub/mailbox/actions/workflows/ci.yml) [](https://github.com/benethos-hub/mailbox/blob/main/LICENSE)

One REST API for all your mailboxes, whichever provider they are at, a Python client for it and an MCP server on top. Scripts, tools and AI agents work with your mail through one door you control.

Status: beta, version 0.4.1. Usable with real
Read from source at commit 69fb543c145aOBSERVED · 2026-10-11
02

Connect

Built from this server's own package name, version and transport as found in its source — not copied from anyone's documentation, so it cannot drift against a page we do not control. Replace the environment placeholders with a token scoped to the least it needs.

claude-code (pypi)
claude mcp add benethos-mailbox-mcp --env MAILBOX_SERVICE_TOKEN=${MAILBOX_SERVICE_TOKEN} -- uvx benethos-mailbox-mcp==0.4.1
03

Trust audit

CAUTIONgrade C · trust 75/100 Install with care. The audit found things worth knowing before you trust its output.

LayerWhat it checksResult
L0Provenance & inventoryPASS
L1Static analysis of the codeWARN
L2Instruction surface (what it tells the agent)WARN
L3Class-specific surfacePASS
L4Behavioural (sandbox)SKIPPED

What the source does

Filesystem
declared (3 observation(s))
Network
declared (6 observation(s))
Shell
none-observed
Dependencies
pinned
Secrets in source
found

Findings (25)

MEDIUMNetwork egress · net.raw_ip · CWE-200, CWE-319
config/benethos-mailbox-mcp/.env.example:11
MAILBOX_SERVICE_URL=http://127.0.0.1:8080
MEDIUMHard-coded secrets · secret.generic · CWE-798, CWE-321
packages/mailbox-service/tests/domain/accounts/test_verify.py:106
server.password = "changed-at-the-provider"
MEDIUMPrompt injection · prompt.hidden_style · CWE-94, CWE-1427
CHANGELOG.md:1168
name: `<div style="display:none">...</span> text</div>` kept `text`
LOWCode injection · code.dynamic_import · CWE-78, CWE-94, CWE-95
packages/mailbox-service/tests/data/storage/test_sqlite.py:303
module.name: importlib.import_module(f"{versions.__name__}.{module.name}")
LOWCode injection · code.dynamic_import · CWE-78, CWE-94, CWE-95
packages/mailbox-service/tests/domain/activity/test_activity.py:65
module = importlib.import_module(f"{catalogue.__name__}.{info.name}")
LOWCode injection · code.dynamic_import · CWE-78, CWE-94, CWE-95
packages/mailbox-service/tests/test_packaging.py:121
module = importlib.import_module(_module(package))
LOWFilesystem / path · fs.traversal · CWE-22, CWE-59
packages/mailbox-service/tests/web/pages/test_ui_icon.py:126
"containers/production/README.md": "../../",
LOWFilesystem / path · fs.traversal · CWE-22, CWE-59
packages/mailbox-service/tests/web/pages/test_ui_icon.py:127
"containers/test-mail-server/README.md": "../../",
LOWNetwork egress · net.metadata_ip · CWE-200, CWE-319
packages/mailbox-service/tests/data/discovery/test_discovery_parts.py:87
("169.254.169.254", False),
Why it matters. cloud metadata endpoint: the classic SSRF credential grab
LOWNetwork egress · net.metadata_ip · CWE-200, CWE-319
packages/mailbox-service/tests/domain/webhooks/test_delivery.py:325
"address", ["169.254.169.254", "fe80::1", "224.0.0.1", "0.0.0.0"]
Why it matters. cloud metadata endpoint: the classic SSRF credential grab
LOWNetwork egress · net.metadata_ip · CWE-200, CWE-319
packages/mailbox-service/tests/domain/webhooks/test_delivery.py:341
("169.254.169.254", False),
Why it matters. cloud metadata endpoint: the classic SSRF credential grab
LOWNetwork egress · net.metadata_ip · CWE-200, CWE-319
packages/mailbox-service/tests/domain/webhooks/test_delivery.py:347
("::ffff:169.254.169.254", False),
Why it matters. cloud metadata endpoint: the classic SSRF credential grab
LOWNetwork egress · net.raw_ip · CWE-200, CWE-319
.github/workflows/ci.yml:302
code=$(curl -s -o /dev/null -w "%{http_code}" http://127.0.0.1:8080/health) || code=000
LOWNetwork egress · net.raw_ip · CWE-200, CWE-319
CLAUDE.md:57
`http://127.0.0.1:8080/ui` as `admin`, choose a password, and make a
LOWNetwork egress · net.raw_ip · CWE-200, CWE-319
CLAUDE.md:83
- The configuration UI: `http://127.0.0.1:8080/ui`, sign in with a user
LOWNetwork egress · net.raw_ip · CWE-200, CWE-319
README.md:178
2. Open `http://127.0.0.1:8080/ui`, sign in as `admin` with the
LOWObfuscation / stealth · obf.decode_call · CWE-506, CWE-94
packages/mailbox-mcp/tests/tools/test_attachments.py:127
png_size(base64.b64decode(pages[0].data))
LOWObfuscation / stealth · obf.decode_call · CWE-506, CWE-94
packages/mailbox-mcp/tests/tools/test_attachments.py:145
assert base64.b64decode(image.data) == picture
LOWObfuscation / stealth · obf.decode_call · CWE-506, CWE-94
packages/mailbox-service/src/benethos_mailbox_service/common/opaque.py:31
return base64.b64decode(padded, _URL_SAFE if url else None, validate=True)
LOWObfuscation / stealth · obf.decode_call · CWE-506, CWE-94
packages/mailbox-service/src/benethos_mailbox_service/data/providers/microsoft/provider.py:228
base64.b64decode(content)
LOWObfuscation / stealth · obf.decode_call · CWE-506, CWE-94
packages/mailbox-service/tests/graph_fake.py:125
self.sent.append(base64.b64decode(request.content))
LOWPrompt injection · prompt.transfer_instruction · CWE-94, CWE-1427
packages/mailbox-mcp/README.md:133
curl -X POST http://127.0.0.1:8080/v1/users/<user id>/tokens \
Why it matters. an instruction to move sensitive data to an outside destination
Fix. remove; a skill never needs the user's secrets off the machine
LOWPrompt injection · prompt.transfer_instruction · CWE-94, CWE-1427
packages/mailbox-service/src/benethos_mailbox_service/web/pages/templates/pages/account_new.html:157
{{ connect_form(discovery.email, {}, suffix="jmap", provider="jmap", password_label="Password or API token", folded=False, primary=False, hint="Choose below which one it is. Tried against the server f
Why it matters. an instruction to move sensitive data to an outside destination
Fix. remove; a skill never needs the user's secrets off the machine
LOWPrompt injection · prompt.transfer_instruction · CWE-94, CWE-1427
packages/mailbox-service/src/benethos_mailbox_service/web/pages/templates/pages/webhook_new.html:10
{% call card("Webhook", meta="Each post is signed with a secret, shown once after creating.") %}
Why it matters. an instruction to move sensitive data to an outside destination
Fix. remove; a skill never needs the user's secrets off the machine
LOWInventory / provenance · mcp.no_tools_extracted · CWE-1104
.github/publish/mcp-registry/server.json
Why it matters. the tool list is enumerated at runtime by tools/list, not declared in source
Fix. the page says so rather than showing an empty table

Gates applied: no_behavioural_pass.

Audited 2026-10-11 · audit v0.4.1 · source sha 69fb543c145afull audit observations/trust-audit/mcp-server/benethos-hub__mailbox.json · Report an issue / request a re-scan
04

Audit history

Every audit this server has had. A grade with a past is a grade somebody is still checking.

DateSourceVerdictGradeScoreChange
2026-10-1169fb543c145aCAUTIONC75first audit
05

Questions

What is the mailbox MCP server?

Self-hosted REST API and web UI for all your mailboxes (IMAP, JMAP, POP3, Gmail, Microsoft 365, Outlook.com), with a Python client and an MCP server so AI agents read, sort, draft and send mail, only within the rights, folders and send limits you grant. Change feed, signed webhooks, audit.

Is mailbox safe to connect to an agent?

With care. The audit graded it C (75/100) and found 25 things worth knowing before you trust this server, listed below with the exact line each was found on.

What credentials does mailbox need?

It reads MAILBOX_SERVICE_TOKEN from the environment. Give it a token scoped to the least it needs — an agent that can be talked into calling a tool can be talked into calling it with your credentials.

How does mailbox run?

It speaks stdio and streamable-http, so it runs as a local process your client starts. It is published on PyPI as benethos-mailbox-service.

How current is this page?

The grade is for one exact copy of the source (69fb543c145a), read on 2026-10-11. The repository is watched and re-audited when it changes.

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