Mail Mcp

mail-mcp

Production-ready email MCP server for AI agents IMAP + SMTP + EWS + Microsoft Graph API — built in Rust

---

Most email MCP servers only do IMAP reads. This one does everything: read, search, send, reply, forward, bulk operations, Microsoft Graph API, and Exchange Web Services — with real OAuth2, multi-account, and multi-provider support. Written in Rust for speed and safety.

What's New in v0.4.8

• SAVE_SENT is now per-account with a provider-aware default.

Previously, saving a copy of outgoing mail to the Sent folder via IMAP APPEND was controlled by a single global flag, MAIL_SMTP_SAVE_SENT. The problem: providers that already save sent mail server-side (Gmail, Zoho) ended up with two identical copies in Sent, while a generic SMTP server or Office 365 (which do not auto-save on SMTP submission) lost the copy entirely when the flag was false.

• Provider-aware default (when nothing is configured):
• Gmail (smtp.gmail.com): saves server-side and deduplicates by

Message-ID → the MCP does not append (false).

• Zoho (smtp.zoho.com): saves server-side but does not

deduplicate → the MCP does not append (false), avoiding the duplicate.

• Office 365 / generic SMTP: do not auto-save on SMTP submission →

the MCP does append (true), or the sent copy would be lost.

• Per-account override: MAIL_SMTP__SAVE_SENT=true|false takes

priority over everything. The global MAIL_SMTP_SAVE_SENT still works as a coarse override (wins over the provider default, loses to the per-account override).

• Precedence: per-account → global → provider-aware default.

| Provider | Auto-saves server-side | MCP default | |---|---|---| | Gmail | Yes (with dedupe) | false | | Zoho | Yes (no dedupe) | false | | Office 365 (SMTP) | No | true | | Generic SMTP / relays | No | true |

What's New in v0.4.7

• **Critical fix — graph_send_message silently dropped attachments on

threaded replies. When called with in_reply_to + attachments, the createReply → PATCH → send flow included the attachments in the PATCH against /me/messages/{id}. Microsoft Graph treats Message.attachments as a navigation property and silently discards the field** on PATCH (2xx response, no error), so the message went out as single-part text/html with no file. The MCP returned status: ok and the caller assumed success. Invisible data loss.

• The fix: in send_via_reply(), attachments are now uploaded one by one

to POST /me/messages/{draft_id}/attachments between the PATCH and the send. Files markup into the recipient's inbox. v0.4.6 adds a real validator that **rejects** the tool call before any SMTP / Graph / EWS attempt if bodytext or bodyhtml contains tool-call wrapper syntax. The check is wired into all 5 send paths (smtpsendmessage, smtpreplymessage, smtpforwardmessage, graphsendmessage, ewssendmessage`).

• The forbidden markers are case-insensitive and tightly scoped — only

the pseudo-tags that have no legitimate use in human correspondence: `, , , , , , , and . Generic technical content that happens to mention for an XML schema or ` in a code example still passes.

• HARD RULE #1 wording updated to announce the server-side rejection,

so the LLM knows it's a hard contract — not a suggestion it can ignore.

• No breaking changes for clean callers: well-behaved messages send

exactly as before.

What's New in v0.4.5

• serverInfo now reports name="mail-mcp" + the crate version (the

framework previously returned its own rmcp 0.16.0, which never changes between releases). Useful for verifying the active version with /mcp, and so any client-side cache keyed by (server, version) invalidates on each bump.

• MCP instructions reorganized: the 3 critical anti-concatenation rules

(which in v0.4.3 and v0.4.4 sat at the end of the block and could be lost to truncation / diluted attention) now appear as HARD RULE #1, #2, #3 at the TOP, right after the title. Consolidated into 3 short paragraphs (previously 3 long sections, ~1500 characters combined).

• No functional changes to the server. Same SMTP/IMAP/EWS/Graph, same

tool set, same behavior. Only the text exposed to the client changed.

Important for these rules to take effect

Clients that resume a session with claude --continue (or /resume) do NOT refresh the MCP system_prompt — they keep the one from that session's first handshake. If your session predates v0.4.5, the rules won't reach your context even if the on-disk binary is updated. To receive them, start a NEW session in the project (not --continue).

What's New in v0.4.4

• Preview hygiene rule in MCP instructions: when the LLM shows the

user the email preview before sending, it should render ONE clean version of the body (markdown-style bullets, bold, links as text + URL) and state that the message will go multipart — but it must NOT dump the raw HTML source (`, , `...) into the preview. Two reasons:

1. The human reviewer wants to read the message, not audit markup —

showing the HTML is noise.

1. Exhibiting both the plain-text string AND the HTML string side by

side in the preview is exactly the context that has historically led LLMs to concatenate them in the eventual tool call (the bug v0.4.3 documented). Hiding the HTML source from the preview removes the temptation.

Complements the PREVIEW DOES NOT EQUAL TOOL CALL rule introduced in v0.4.3.

What's New in v0.4.3

• Server-side guidance against malformed tool calls. The MCP

instructions block now explicitly tells the calling LLM that body_text and body_html are TWO SEPARATE JSON fields and must NEVER be concatenated. Previous wording ("send BOTH bodytext AND bodyhtml") was ambiguous and some LLMs interpreted it as "concatenate both with ... pseudo-tags inside a single body_text string". When that happens, the recipient sees garbled duplicated content, AND any later Claude session that opens the saved copy via this MCP gets a Usage Policy block (the leaked ... looks like a prompt-injection attempt to safety filters). The new instruction shows a CORRECT vs WRONG example and bans pseudo-tags / tool-call wrapper syntax inside email fields.

What's New in v0.4.2

• Release pipeline fixed: the publish-npm job in the CI release

workflow has been disabled. It was inherited from the upstream fork and tried to publish to @bradsjm/mail-imap-mcp-rs, a scope this org does not own — every release was 404-ing on that step. See "Releasing" below for the full explanation and how to re-enable npm publishing if needed.

• Auto-trigger releases on tag push: .github/workflows/release.yml

now fires on push: tags: ['v*'], so tagging vX.Y.Z and pushing is all it takes to cut a release. workflow_dispatch is retained as a manual escape hatch.

• Cleanup: removed the dangling init-npm-placeholder.yml workflow

(also referenced the fork's npm scope).

• docs: README gains a "Releasing" section documenting the new flow

and the npm decision.

What's New in v0.4.1

• Fix: save_to_sent_folder now archives the exact RFC822 bytes that were

sent (via lettre.formatted()), instead of a hand-rolled text-only stub. The Sent-folder copy keeps the HTML body, the multipart/alternative structure, and the RFC 2047-encoded subject — no more ??? where accents used to be, and HTML is no longer silently dropped.

• Improved: localized Sent-folder detection — Enviado[s], `Elementos

enviados, Enviadas, Itens enviados, Envoyés, Éléments envoyés, Gesendet, Posta inviata, Verzonden, Wysłane, plus nested variants. Previously only English names were recognized, so Zoho/localized IMAP accounts fell through to a non-existent "Sent"` folder.

• Improved: smtp_forward_message accepts body_html (was hardcoded to

plain-text only).

• Improved: EWS send gains bcc, in_reply_to, references (via

``), plus full recipient + subject-length validation — now at parity with the SMTP and Graph send paths.

• Improved: Graph API threading fallbacks now log. WARN when the

message-lookup HTTP call fails (rate limit, 5xx, permissions) so operators see threading degraded due to a real error; DEBUG when the original message is legitimately not found.

• Refactor: EWS XML parsing migrated from substring matching to

quick-xml. Fixes a latent namespace-collision bug (` vs ), correctly decodes XML entities and CDATA, and handles attribute values containing =` (common in base64-like EWS item IDs).

• Cleanup: zero warnings on cargo build --release.
• Tests: 64 (up from 47).

Why This Project

| | mail-mcp | Typical email MCP | |---|:---:|:---:| | IMAP read/write | 18 tools | 3-5 tools | | SMTP send/reply/forward | Yes | No or broken | | Microsoft Graph API | Yes | No | | EWS (Exchange Web Services) | Yes | No | | OAuth2 (XOAUTH2) | Native | No | | Multi-account | Yes | Single account | | Microsoft 365 + Hotmail | Both work | Usually neither | | Language | Rust (fast, safe) | TypeScript/Python | | Tests | 64 unit + integration | Mocks only | | Warnings in release build | 0 | Varies |

Feature Matrix

| Provider | IMAP | SMTP | Graph API | EWS | OAuth2 | Multi-account | |----------|:----:|:----:|:---------:|:---:|:------:|:-------------:| | Microsoft 365 (enterprise) | Yes | Admin-dependent | Yes | Yes | Yes | Yes | | Hotmail / Outlook.com | Yes | Blocked by MS | Yes | Yes | Yes | Yes | | Gmail | Yes | Yes | — | — | Yes | Yes | | Zoho | Yes | Yes | — | — | — | Yes | | Fastmail | Yes | Yes | — | — | — | Yes | | Any IMAP/SMTP server | Yes | Yes | — | — | — | Yes |

> EWS is the simplest way to add Microsoft accounts — single OAuth2 token for both reading and sending. Works even on tenants that block Graph API and IMAP.

Quickstart — Let Claude Code do it

Copy and paste this prompt into Claude Code and it will install, compile, and configure everything for you:

Install and configure the mail-mcp MCP server from https://github.com/tecnologicachile/mail-mcp

1. Clone the repo, build with cargo build --release
2. Add the MCP server to .claude.json with the binary path
3. For Microsoft accounts: use EWS (simplest) — run device code flow with
   client_id d3590ed6-52b3-4102-aeff-aad2292ab01c and scope
   https://outlook.office365.com/EWS.AccessAsUser.All offline_access
   Then configure MAIL_EWS__USER and MAIL_EWS__REFRESH_TOKEN
4. For Gmail: configure MAIL_IMAP + MAIL_SMTP with App Password from
   https://myaccount.google.com/apppasswords
5. For Zoho: configure MAIL_IMAP + MAIL_SMTP with standard password
6. Enable write/send: MAIL_IMAP_WRITE_ENABLED=true, MAIL_SMTP_WRITE_ENABLED=true

My email accounts to configure:
- 

Replace the last line with your email(s). Claude Code will guide you through each step including the OAuth2 device code flow for Microsoft accounts.

Manual Setup (2 minutes)

git clone https://github.com/tecnologicachile/mail-mcp.git
cd mail-mcp
cargo build --release

Add to your MCP client config (Claude Code, Cursor, etc.):

{
  "mcpServers": {
    "mail": {
      "command": "./target/release/mail-mcp",
      "env": {
        "MAIL_IMAP_DEFAULT_HOST": "imap.gmail.com",
        "MAIL_IMAP_DEFAULT_USER": "you@gmail.com",
        "MAIL_IMAP_DEFAULT_PASS": "your-app-password",
        "MAIL_SMTP_DEFAULT_HOST": "smtp.gmail.com",
        "MAIL_SMTP_DEFAULT_PORT": "587",
        "MAIL_SMTP_DEFAULT_USER": "you@gmail.com",
        "MAIL_SMTP_DEFAULT_PASS": "your-app-password",
        "MAIL_SMTP_DEFAULT_SECURE": "starttls",
        "MAIL_IMAP_WRITE_ENABLED": "true",
        "MAIL_SMTP_WRITE_ENABLED": "true"
      }
    }
  }
}

That's it. Your AI agent can now read, search, send, reply, and manage emails.

Microsoft Account? Use Graph API

Microsoft blocks SMTP on personal accounts. Use Graph API instead:

{
  "env": {
    "MAIL_IMAP_DEFAULT_HOST": "outlook.office365.com",
    "MAIL_IMAP_DEFAULT_USER": "you@hotmail.com",
    "MAIL_IMAP_DEFAULT_PASS": "your-app-password",
    "MAIL_OAUTH2_DEFAULT_PROVIDER": "microsoft",
    "MAIL_OAUTH2_DEFAULT_CLIENT_ID": "9e5f94bc-e8a4-4e73-b8be-63364c29d753",
    "MAIL_OAUTH2_DEFAULT_CLIENT_SECRET": "none",
    "MAIL_OAUTH2_DEFAULT_REFRESH_TOKEN": ""
  }
}

Get your token in 1 minute with device code flow. See [Account Setup Guide](docs/account-setup.md).

30 MCP Tools

Read (8 tools)

| Tool | What it does | |------|-------------| | list_all_accounts | List all accounts with capabilities (IMAP, SMTP, Graph, EWS) | | imap_list_accounts | List IMAP accounts | | imap_verify_account | Test connectivity and auth | | imap_list_mailboxes | List folders | | imap_mailbox_status | Message counts | | imap_search_messages | Search with cursor pagination | | imap_get_message | Parsed message (text, HTML, attachments) | | imap_get_message_raw | RFC822 source |

Write (11 tools)

| Tool | What it does | |------|-------------| | imap_update_message_flags | Add/remove flags | | imap_copy_message | Copy (cross-account supported) | | imap_move_message | Move to folder | | imap_delete_message | Delete with confirmation | | imap_create_mailbox | Create folder | | imap_delete_mailbox | Delete folder | | imap_rename_mailbox | Rename folder | | imap_append_message | Append raw message | | imap_bulk_move | Move up to 500 at once | | imap_bulk_delete | Delete up to 500 at once | | imap_bulk_update_flags | Flag up to 500 at once |

Send (5 tools)

| Tool | What it does | |------|-------------| | smtp_send_message | Send email (text/HTML, CC/BCC) | | smtp_reply_message | Reply with threading headers | | smtp_forward_message | Forward with original inline | | smtp_verify_account | Test SMTP connectivity | | graph_send_message | Send via Microsoft Graph API (with reply threading) |

EWS — Exchange Web Services (3 tools)

| Tool | What it does | |------|-------------| | ews_search_messages | Search emails via EWS (inbox, sent, drafts, etc.) | | ews_get_message | Get full email content via EWS | | ews_send_message | Send email via EWS |

Attachments

Send files with any send tool. Two modes:

// Large files — MCP reads from disk (recommended)
"attachments": [{"file_path": "/path/to/report.pdf"}]

// Small files — inline base64
"attachments": [{"filename": "note.txt", "content_type": "text/plain", "content_base64": "SGVsbG8="}]

Filename and MIME type are auto-detected from the file path. Reply with include_original_attachments: true to forward original attachments.

Bulk Operations (2 tools)

| Tool | What it does | |------|-------------| | imap_search_and_move | Search + move matches | | imap_search_and_delete | Search + delete matches |

Setup Helper (1 tool)

| Tool | What it does | |------|-------------| | get_setup_guide | Provider-specific setup instructions (Microsoft OAuth2, Gmail App Passwords, Zoho, etc.) |

Multi-Account

Configure as many accounts as you need:

# Gmail
MAIL_IMAP_GMAIL_HOST=imap.gmail.com
MAIL_IMAP_GMAIL_USER=me@gmail.com
MAIL_IMAP_GMAIL_PASS=app-password

# Microsoft 365
MAIL_IMAP_WORK_HOST=outlook.office365.com
MAIL_IMAP_WORK_USER=me@company.com
MAIL_OAUTH2_WORK_PROVIDER=microsoft
MAIL_OAUTH2_WORK_CLIENT_ID=your-client-id
MAIL_OAUTH2_WORK_CLIENT_SECRET=none
MAIL_OAUTH2_WORK_REFRESH_TOKEN=your-token

# Zoho
MAIL_IMAP_DEFAULT_HOST=imap.zoho.com
MAIL_IMAP_DEFAULT_USER=info@mydomain.com
MAIL_IMAP_DEFAULT_PASS=password
MAIL_SMTP_DEFAULT_HOST=smtp.zoho.com
MAIL_SMTP_DEFAULT_USER=info@mydomain.com
MAIL_SMTP_DEFAULT_PASS=password
MAIL_SMTP_DEFAULT_SE

…

## Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [tecnologicachile](https://github.com/tecnologicachile)
- **Source:** [tecnologicachile/mail-mcp](https://github.com/tecnologicachile/mail-mcp)
- **License:** MIT

Install and usage instructions live in the source repository linked above.