io.github.nikolausm/imap-mcp-server MCP Server

IMAP MCP Server

A powerful Model Context Protocol (MCP) server that provides seamless IMAP email integration with secure account management and connection pooling.

Features

• 🔐 Secure Account Management: Encrypted credential storage with AES-256 encryption
• 🚀 Connection Pooling: Efficient IMAP connection management
• 📧 Comprehensive Email Operations: Search, read, move, mark, delete, and bulk delete emails
• ✉️ Email Sending: Send, reply, and forward emails via SMTP
• 📁 Folder Management: List folders, check status, get unread counts
• 🔄 Multiple Account Support: Manage multiple IMAP accounts simultaneously
• 🛡️ Type-Safe: Built with TypeScript for reliability
• 🌐 Web-Based Setup Wizard: Easy account configuration with provider presets
• 📱 15+ Email Providers: Pre-configured settings for Gmail, Outlook, Yahoo, and more
• 🔗 Auto SMTP Configuration: Automatic SMTP settings based on IMAP provider

Installation

Requires Node.js 22.12 or newer. Node 18 and 20 have both reached end-of-life, and several of this package's dependencies no longer support them. Check yours with node --version.

Run via npx (No Installation Required)

Once published to npm, you can run the server directly without cloning or building anything — npx downloads the prebuilt package and runs it:

npx -y imap-mcp-server

This is the easiest way to use the server in an MCP client (see Configuration for ready-to-paste npx configs).

Quick Install (Recommended)

macOS/Linux:

curl -fsSL https://raw.githubusercontent.com/nikolausm/imap-mcp-server/main/install.sh | bash

Windows (PowerShell as Administrator):

iwr -useb https://raw.githubusercontent.com/nikolausm/imap-mcp-server/main/install.ps1 | iex

Manual Installation

1. Clone the repository:

git clone https://github.com/nikolausm/imap-mcp-server.git
cd imap-mcp-server

2. Install dependencies:

npm install

3. Build the project:

npm run build

Account Setup

Accounts are stored encrypted in ~/.imap-mcp/accounts.json. This file is shared by all run modes — whether you start the server via npx, a global install, or a local clone, they all read the same accounts. So you only need to set up your accounts once.

Setting Up Accounts in npx Mode

If you run the server via npx (no clone), you have two ways to add accounts:

Option A — Run the setup wizard directly via npx (no install needed):

npx -p imap-mcp-server imap-setup

This launches the same web-based wizard described below and writes to ~/.imap-mcp/accounts.json, which your npx-configured MCP server then picks up automatically.

Option B — Add accounts straight from your AI client:

Once the MCP server is configured, just ask your assistant to add an account — it uses the imap_add_account tool. For example:

"Add my IMAP account: host imap.gmail.com, port 993, user me@gmail.com, password …"

No separate setup step required.

Web-Based Setup Wizard (Recommended)

After installation, run the setup wizard:

npm run setup

Or if installed globally:

imap-setup

Or directly via npx without installing:

npx -p imap-mcp-server imap-setup

This will:

1. Start a local web server
2. Open your browser to the setup wizard
3. Guide you through adding email accounts with pre-configured settings

Overriding Credentials via Environment Variables

You can override the username and password of an already-configured account at runtime with environment variables — useful when you inject secrets from a password manager or CI system instead of storing them in accounts.json.

The variables are keyed by the account name, uppercased with every non-alphanumeric character replaced by _. For an account named Work Gmail (key WORK_GMAIL):

Variable	Overrides
IMAP_MCP_ACCOUNT_WORK_GMAIL_IMAP_USERNAME	IMAP username (user)
IMAP_MCP_ACCOUNT_WORK_GMAIL_IMAP_PASSWORD	IMAP password
IMAP_MCP_ACCOUNT_WORK_GMAIL_SMTP_USERNAME	SMTP username (smtp.user)
IMAP_MCP_ACCOUNT_WORK_GMAIL_SMTP_PASSWORD	SMTP password

Notes:

• Overrides apply only to existing accounts; if no account's normalized name matches, the variable is ignored.
• They are applied in memory only — nothing is written back to accounts.json, and the values are used as-is (not re-encrypted).
• Variables are consumed at startup: on server start they are captured into an AES-256-encrypted in-memory cache and removed from process.env, so the plaintext secret does not linger in the environment (where it could leak to child processes or diagnostics). Set them before launching the server.

The setup wizard integrates with this: each credential field (IMAP password, IMAP username, SMTP username, SMTP password) has a "Do not save to config; set later using an environment variable" checkbox. When ticked, the value you enter is still used to test the connection, but it is not written to accounts.json — the wizard shows the exact variable name to export, and the account picks the credential up from that variable at runtime.

• SMTP variables take effect only when the account already has an SMTP config.
• Each variable takes effect independently; set only the ones you need.

If the variable is missing, the account still holds the empty placeholder the wizard wrote. Rather than dialing out with a blank credential — which providers answer with a generic authentication failure that looks exactly like a wrong password — the server refuses the connection and names what to set:

Account "Work Gmail" has IMAP credentials marked as environment-managed, but
this variable was not set when the server started:
IMAP_MCP_ACCOUNT_WORK_GMAIL_IMAP_PASSWORD. Set it and restart the server, or
store the credentials on the account via imap_update_account.

Because the variables are read once at startup, setting one in an already-running shell has no effect until the server is restarted.

Supported Email Providers

The setup wizard includes pre-configured settings for:

• Gmail / Google Workspace
• Microsoft Outlook / Hotmail / Live
• Yahoo Mail
• Apple iCloud Mail
• GMX
• WEB.DE
• IONOS (1&1)
• ProtonMail (with Bridge)
• Fastmail
• Zoho Mail
• AOL Mail
• mailbox.org
• Posteo
• Custom IMAP servers

Configuration

Claude Code (CLI)

Option A — via npx (no clone/build needed)

claude mcp add imap -- npx -y imap-mcp-server

This always runs the latest published version and requires no local build.

Option B — from a local clone

If you use Claude Code in the terminal, add the MCP server with a single command:

Step 1: Make sure you have built the project first (see Manual Installation).

Step 2: Run this command in your terminal:

claude mcp add imap -- node /absolute/path/to/imap-mcp-server/dist/index.js

Important: Replace /absolute/path/to/imap-mcp-server with the actual path where you cloned the repository. For example:

# macOS/Linux example:
claude mcp add imap -- node /Users/yourname/imap-mcp-server/dist/index.js

# Windows example:
claude mcp add imap -- node C:\Users\yourname\imap-mcp-server\dist\index.js

Step 3: Verify it was added:

claude mcp list

You should see imap in the list of configured MCP servers. That's it — the IMAP tools are now available in your Claude Code sessions.

Tip: If you want to remove the server later, run:

claude mcp remove imap

Claude Desktop (GUI App)

Add the IMAP MCP server to your Claude Desktop configuration file:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json Windows: %APPDATA%\Claude\claude_desktop_config.json

Option A — via npx (recommended, no clone/build needed):

{
  "mcpServers": {
    "imap": {
      "command": "npx",
      "args": ["-y", "imap-mcp-server"],
      "env": {}
    }
  }
}

Option B — from a local clone:

{
  "mcpServers": {
    "imap": {
      "command": "node",
      "args": ["/path/to/imap-mcp-server/dist/index.js"],
      "env": {}
    }
  }
}

Restricting tool access (read-only mode / allowlist)

By default all tools are exposed. You can restrict which tools the agent sees using two environment variables (set them under the env key of your MCP config). This is useful when you want to give an assistant read-only access to a mailbox, or expose only a hand-picked subset of tools.

Variable	Effect
IMAP_MCP_READ_ONLY	When truthy (1, true, yes, on), only the safe, read-only tools are registered — searching, reading, listing folders, unread counts, spam analysis. No tool that sends mail, deletes/moves messages, changes flags, or edits accounts is exposed.
IMAP_MCP_ENABLED_TOOLS	Comma-separated allowlist of tool names — only these are registered. Names are case-insensitive and the imap_ prefix is optional (search_emails ≡ imap_search_emails). When set, it takes precedence over IMAP_MCP_READ_ONLY.

Example — read-only access:

{
  "mcpServers": {
    "imap": {
      "command": "npx",
      "args": ["-y", "imap-mcp-server"],
      "env": { "IMAP_MCP_READ_ONLY": "true" }
    }
  }
}

Example — explicit allowlist:

{
  "mcpServers": {
    "imap": {
      "command": "npx",
      "args": ["-y", "imap-mcp-server"],
      "env": { "IMAP_MCP_ENABLED_TOOLS": "imap_search_emails,imap_get_email,imap_get_latest_emails" }
    }
  }
}

The read-only subset is: imap_list_accounts, imap_connect, imap_disconnect, imap_test_account, imap_search_emails, imap_get_email, imap_get_latest_emails, imap_download_attachment, imap_find_thread_messages, imap_find_email_by_message_id, imap_list_folders, imap_folder_status, imap_get_unread_count, imap_check_spam, imap_domain_stats, imap_list_spam_domains.

Usage

Once configured, the IMAP MCP server provides the following tools in Claude:

Choosing an account. For the email and folder tools, accountId is optional and backward-compatible. You may instead pass accountName, and if you only have a single account configured you can omit both — that account is used by default. With multiple accounts and no selector, the tool returns a clear error listing your options (imap_list_accounts).

Account Management

• imap_add_account: Add a new IMAP account

  Parameters:
  - name: Friendly name for the account
  - host: IMAP server hostname
  - port: Server port (default: 993)
  - user: Username
  - password: Password
  - tls: Use TLS/SSL (default: true)
  - sentFolder: Explicit Sent-folder name for sent-mail copies, e.g. "Gesendet"
      (optional — only needed when the server has no \Sent SPECIAL-USE folder
      and auto-detection fails)
  - defaultBcc: Optional BCC address(es) applied automatically to every
      outbound send, reply, forward, and draft for this account. Merged with
      any per-call `bcc` (duplicates removed case-insensitively)
  

• imap_update_account: Update an existing account (fix SMTP settings, rename, etc.)

  Parameters:
  - accountId: ID of the account to update
  - name, host, port, user, password, tls, email: IMAP fields (all optional)
  - smtpHost, smtpPort, smtpSecure, smtpUser, smtpPassword: SMTP fields (optional)
  - saveToSent: Save sent emails to the Sent folder (optional)
  - sentFolder: Explicit Sent-folder override (optional). Pass an empty string
      to clear the override and re-enable auto-detection
  - defaultBcc: Optional default BCC address(es) (optional). Pass an empty
      string to clear
  

• imap_list_accounts: List all configured accounts

• imap_remove_account: Remove an account

  Parameters:
  - accountId: ID of the account to remove
  

• imap_connect: Connect to an account

  Parameters:
  - accountId OR accountName: Account identifier
  

• imap_disconnect: Disconnect from an account

  Parameters:
  - accountId: Account to disconnect
  

Email Operations

• imap_search_emails: Search for emails

  Parameters:
  - accountId: Account ID
  - folder: Folder name (default: INBOX; ignored when searchAllFolders is true)
  - searchAllFolders: Search across ALL folders at once (default: false).
      Skips Trash/Spam/Drafts and non-selectable folders by default. Use when a
      message may have been filed/moved/archived and you don't know its folder.
  - includeTrash, includeSpam, includeDrafts: Opt those noisy folders back into
      a searchAllFolders run (default: false each)
  - from, to, subject, body: Search criteria
  - since, before: Date filters
  - seen, flagged: Status filters
  - keywords: Match messages with ANY of these custom keywords (server-side OR).
      Read a mailbox's available custom keywords from `imap_folder_status`'s
      `customKeywords` field first.
  - unKeywords: Exclude messages with ANY of these custom keywords (result has
      NONE of them). Same keyword source as `keywords`.
  - limit: Max results (default: 50)
  - includeBody: Include parsed message body in the response (default: false).
      Fetches the RFC822 source once and parses it with mailparser, so you get
      uid + body in a single tool call instead of paying the N+1 cost of one
      `imap_get_email` per match. Body is rendered per `bodyFormat` and capped
      at `bodyMaxLength` per field.
  - bodyFormat: How to render the body when `includeBody` is true — `markdown`
      (default, clean Markdown via Turndown), `text`, `html`, or `auto`.
  - bodyMaxLength: Per-field cap when `includeBody` is true (default: 10000).
  

  With searchAllFolders, results include a folder field per message plus foldersSearched, and any folder that failed to open is reported in foldersErrored (so a 0-result answer is never silently incomplete).

  includeBody is honored in the single-folder path only. For a cross-folder sweep the lightweight header shape is preserved by design — pulling RFC822 source for every match across many folders would multiply bandwidth and parse cost. Follow up with imap_get_email for the specific uids whose bodies you need.

  On some servers a "flagged"/starred message carries a custom keyword (e.g. an Open-Xchange color label or Apple's $MailFlagBit*) instead of, or in addition to, the \Flagged system flag — after any flagged search, check each result's customKeywords field before concluding a message is or isn't flagged.

• imap_get_email: Get full email content

  Parameters:
  - accountId: Account ID
  - folder: Folder name
  - uid: Email UID
  - maxContentLength: Max characters for text/html body (default: 10000)
  - includeAttachmentText: Include text attachment previews (default: true)
  - maxAttachmentTextChars: Max characters per text attachment (default: 100000)
  

• imap_get_latest_emails: Get recent emails

  Parameters:
  - accountId: Account ID
  - folder: Folder name (default: INBOX)
  - count: Number of emails (default: 10)
  - includeBody: Include parsed message body (default: false). Same semantics
      as the `includeBody` option on `imap_search_emails` — one round-trip
      instead of N×`imap_get_email`.
  - bodyFormat: `markdown` (default), `text`, `html`, or `auto`.
  - bodyMaxLength: Per-field cap (default: 10000).
  

• imap_mark_as_read/unread: Change email read status

  Parameters:
  - accountId: Account ID
  - folder: Folder name
  - uid: Email UID, OR an array of UIDs to flag in one call. Batch uses a
      single IMAP STORE so the operation is atomic at the server level — all
      UIDs are flagged, or none. Useful when triaging many messages at once.
  

• imap_flag_email/unflag_email: Star/unstar an email (sets or clears the IMAP \Flagged system flag — shows as a "star" in Gmail and Apple Mail). Some servers/clients (Open-Xchange, Apple Mail) also set a separate custom keyword (e.g. $cl_N, $MailFlagBit*) when flagging; unflag only clears \Flagged, so if a message still shows as flagged, check customKeywords via imap_get_email and clear it with imap_remove_keyword.

  Parameters:
  - accountId: Account ID
  - folder: Folder name
  - uid: Email UID
  

• imap_add_keyword/remove_keyword: Set or clear an arbitrary custom (non-system) IMAP keyword/label on an email, passed through verbatim (e.g. provider color labels like Open-Xchange's $cl_1..$cl_10 or Apple Mail's $MailFlagBit0..$MailFlagBit2, or any other custom keyword). Backslash-prefixed system flags (e.g. \Flagged, \Seen, \Deleted) are rejected — use the dedicated flag/read tools for those. Not every server permits custom-keyword changes (see the mailbox's PERMANENTFLAGS); if the server rejects or silently ignores the change, the call fails instead of reporting success.

  Parameters:
  - accountId: Account ID
  - folder: Folder name
  - uid: Email UID
  - keyword: IMAP keyword to set/remove (e.g. "$cl_3")
  

• imap_delete_email: Delete an email

  Parameters:
  - accountId: Account ID
  - folder: Folder name
  - uid: Email UID
  

• imap_move_email: Move an email from one folder to another

  Parameters:
  - accountId: Account ID
  - folder: Source folder name (default: INBOX)
  - uid: Email UID, OR an array of UIDs to move in one call. Batch moves are
      attributed per-uid in the response (`results[]` with per-uid `uidMap`
      and any errors). Single-uid calls return the legacy response shape.
  - targetFolder: Destination folder name
  - createDestinationIfMissing: Create the destination folder if it does not exist (default: false)
  

• imap_find_thread_messages: Find inbox messages that belong to the same conversation threads as messages already sorted into another folder. Uses RFC 3501 HEADER search on In-Reply-To and References — works on any IMAP server.

  Parameters:
  - accountId: Account ID
  - sourceFolder: Folder containing the already-sorted thread messages
  - searchFolder: Folder to search for related messages (default: INBOX)
  - searchReferences: Also match the References header for multi-level threads (default: true)
  - includeBody: Include parsed message body for each found thread message
      (default: false). Same semantics as the `includeBody` option on
      `imap_search_emails` — one round-trip instead of N×`imap_get_email`.
  - bodyFormat: `markdown` (default), `text`, `html`, or `auto`.
  - bodyMaxLength: Per-field cap (default: 10000).
  

• imap_download_attachment: Download an email attachment (returns images inline, extracts text from PDFs, or saves to downloads directory)

  Parameters:
  - accountId: Account ID
  - folder: Folder name (default: INBOX)
  - uid: Email UID
  - filename: Attachment filename or contentId
  - savePath: Optional file path to save the attachment to
  - extractText: For PDFs, extract and return text content inline (default: true)
  

• imap_bulk_delete: Delete multiple emails at once with chunking and auto-reconnection

  Parameters:
  - accountId: Account ID
  - folder: Folder name (default: INBOX)
  - uids: Array of email UIDs to delete
  - chunkSize: Emails to delete per batch (default: 50)
  

• imap_bulk_delete_by_search: Search for emails matching criteria and delete them all

  Parameters:
  - accountId: Account ID
  - folder: Folder name (default: INBOX)
  - from, to, subject: Search criteria (optional)
  - before, since: Date filters (optional)
  - chunkSize: Emails to delete per batch (default: 50)
  - dryRun: Preview what would be deleted without deleting (default: false)
  

  At least one concrete criterion (from, to, subject, before, or since) is required — a call with no criteria is refused, so it can never match and delete an entire folder.

• imap_send_email: Send a new email

  Parameters:
  - accountId: Account ID to send from
  - to: Recipient email address(es) — an array, or a single comma-separated string
  - subject: Email subject
  - text: Plain text content (optional)
  - html: HTML content (optional)
  - cc: CC recipients (optional)
  - bcc: BCC recipients (optional)
  - replyTo: Reply-to address (optional)
  - attachments: Array of attachments (optional)
    - filename: Attachment filename
    - content: Base64 encoded content
    - path: File path to attach
    - contentType: MIME type
    - contentDisposition: "attachment" (default) or "inline" — use "inline" for images shown in the HTML body via cid:
    - cid: Content-ID for inline attachments; must match the `cid:` value used in an `<img src="cid:...">` tag in `html`
  

  After sending, a copy is saved to the account's Sent folder (unless saveToSent is disabled on the account). The folder is resolved via the account's sentFolder override → the server's \Sent SPECIAL-USE flag → a list of known localized names ("Sent", "Gesendet", "Éléments envoyés", …). The response reports the outcome: savedToSent (boolean), sentFolder (the folder used), and — when the save fails — sentSaveError explaining why, instead of failing silently. The same applies to imap_reply_to_email and imap_forward_email.

  When the account has defaultBcc configured, those address(es) are always BCC'd on send, reply, forward, and draft (merged with any per-call bcc; duplicates removed case-insensitively).

• imap_save_draft: Save an email as a draft (no send). Takes the same fields as imap_send_email, plus inReplyTo, references, and an optional folder override for the Drafts folder.

• imap_reply_to_email: Reply to an existing email

  Parameters:
  - accountId: Account ID
  - folder: Folder containing the original email
  - uid: UID of the email to reply to
  - text: Plain text reply content (optional)
  - html: HTML reply content (optional)
  - replyAll: Reply to all recipients (default: false)
  - bcc: BCC recipients (optional; merged with account defaultBcc)
  - attachments: Array of attachments (optional, same shape as imap_send_email, including contentDisposition/cid for inline images)
  

• imap_forward_email: Forward an existing email

  Parameters:
  - accountId: Account ID
  - folder: Folder containing the original email
  - uid: UID of the email to forward
  - to: Forward to email address(es)
  - text: Additional text to include (optional)
  - bcc: BCC recipients (optional; merged with account defaultBcc)
  - includeAttachments: Include original attachments (default: true)
  

Folder Operations

• imap_list_folders: List all folders

  Parameters:
  - accountId: Account ID
  

  Each folder includes its attributes (raw IMAP LIST flags) and, when the server advertises it, specialUse — the RFC 6154 role (\Sent, \Drafts, \Trash, \Junk, \Archive) that identifies a folder independent of its localized display name (e.g. "Gesendet" carries specialUse: "\Sent").

• imap_folder_status: Get folder information

  Parameters:
  - accountId: Account ID
  - folder: Folder name
  
  Returns:
  - messages: { total, new, unseen } — from IMAP STATUS
  - uidvalidity, uidnext
  - flags, permanentFlags: string arrays
  - customKeywords: the mailbox's non-system keywords, usable as the
      `keywords` / `unKeywords` input of imap_search_emails
  

• imap_create_folder: Create a new IMAP folder/mailbox. Most servers also create any missing parent folders. Returns success even if the folder already exists.

  Parameters:
  - accountId: Account ID
  - folder: Full folder path to create (e.g. "Archives/2026/2026-05" or "INBOX.Archive")
  

• imap_get_unread_count: Count unread emails

  Parameters:
  - accountId: Account ID
  - folders: Specific folders (optional)
  

Security

• Credentials are encrypted using AES-256-CBC encryption
• Encryption keys are stored separately in ~/.imap-mcp/.key
• Account configurations are stored in ~/.imap-mcp/accounts.json
• The store directory, .key, and accounts.json are written owner-only (0700/0600) so other local users cannot read the key or the credentials
• The web setup wizard's HTTP API never returns stored passwords to the browser
• Downloaded attachments are confined to the downloads directory; sender-supplied filenames cannot write outside it
• Never commit or share your encryption key or account configurations

Development

Running in Development Mode

npm run dev

Building

npm run build

Project Structure

src/
├── index.ts           # MCP server entry point
├── services/
│   ├── imap-service.ts    # IMAP connection management
│   ├── smtp-service.ts    # SMTP service for sending emails
│   └── account-manager.ts # Account configuration
├── tools/
│   ├── index.ts          # Tool registration
│   ├── account-tools.ts  # Account management tools
│   ├── email-tools.ts    # Email operation tools (including send/reply/forward)
│   └── folder-tools.ts   # Folder operation tools
└── types/
    └── index.ts          # TypeScript type definitions

Example Usage in Claude

1. Add an account: "Add my Gmail account with username john@gmail.com"

2. Check new emails: "Show me the latest 5 emails from my Gmail account"

3. Search emails: "Search for emails from boss@company.com in the last week"

4. Send an email: "Send an email to client@example.com with subject 'Project Update'"

5. Reply to emails: "Reply to the latest email from my boss"

6. Forward emails: "Forward the email with subject 'Meeting Notes' to team@company.com"

7. Move an email: "Move the invoice email from INBOX to my Taxes folder"

8. Manage folders: "List all folders in my email account and show unread counts"

Troubleshooting

Connection Issues

• Ensure your IMAP server settings are correct
• Check if your email provider requires app-specific passwords
• Verify that IMAP is enabled in your email account settings
• For sending emails, ensure your account has SMTP access enabled

Recipients arriving as ["a@x.com","b@y.com"]

to, cc, bcc, references and uid accept either a single value or an array. In JSON Schema that is an anyOf, and some MCP clients drop the anyOf before showing the schema to the model — the field then looks untyped or string-typed, and the client serializes the model's array into a string. The server used to pass that string straight to nodemailer, which folded the literal [ and ] into the first and last address, so every recipient was rejected by the receiving mail server (issue #127).

The server now detects a stringified array and restores it, both when validating tool input and again before composing the message, and logs a warning to stderr naming the field. Nothing needs to change on your side. If you want to bypass the client behavior entirely, pass recipients as one comma-separated string: "Alice <alice@example.com>, Bob <bob@example.org>".

SMTP Configuration

The server automatically configures SMTP settings based on your IMAP provider. If you need custom SMTP settings, you can specify them when adding an account:

{
  "smtp": {
    "host": "smtp.example.com",
    "port": 587,
    "secure": false
  }
}

Common IMAP Settings

• Gmail:

  • Host: imap.gmail.com
  • Port: 993
  • Requires app-specific password

• Outlook/Hotmail:

  • Host: outlook.office365.com
  • Port: 993

• Yahoo:

  • Host: imap.mail.yahoo.com
  • Port: 993
  • Requires app-specific password

License

MIT

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.