Carrier - Rust MCP server for Sulkta email. 10 tools, multi-account, attachment-safe.

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Kayos b681953824 Phase C: mail_mark, mail_attachment_get, mail_reply Three new tools complete the planned Phase C scope: - mail_mark { uid, action, folder? }: action is one of read, unread, flagged, unflagged, trash, archive. read/unread toggle \Seen via UID STORE +/-FLAGS.SILENT (idempotent, no fetch round-trip). flagged/ unflagged the same for \Flagged. trash is a MOVE to Trash. archive errors out with a clear pointer to mail_move because Sulkta's Dovecot doesn't ship a canonical Archive folder. - mail_attachment_get { uid, attachment_index, folder? }: fetches the full RFC822 (within the existing 20 MB raw_eml cap), parses with mail-parser, returns the N-th attachment as base64. The index matches mail_inbox_read's attachments[] ordering. Returns {filename, mime_type, size, content_base64}. SAFETY note in the tool description warns the LLM not to execute / render / open attachment bytes blindly. - mail_reply { uid, body, body_html?, attachments?, reply_all?, to_override? }: fetches the original to pull From / Subject / Message-Id / References, then sends with proper In-Reply-To + References + 'Re: ' subject prefix (skipped if already prefixed). reply_all=true echoes the original Cc. to_override replaces To. Threading headers still set against the original regardless of to_override. Smoke verified 2026-05-21: - Send kayos->kayos with a 54-byte text attachment - mail_inbox_read shows attachments=[('smoke.txt', 54)] - mail_attachment_get returns the exact bytes (b'Hello from mail-mcp Phase C smoke!\r\nLine 2.\r\nLine 3.\r\n', 54 bytes) - mail_mark unread -> flags=[] (\Seen cleared) - mail_mark flagged -> flags=['\\Flagged'] - mail_reply -> message lands as 'Re: mail-mcp phase-C smoke' with In-Reply-To = parent Message-Id and References = parent Message-Id ServerHandler instructions updated to enumerate all 10 tools + the new attachment-safety note. Tools live on the wire: mail_send, mail_inbox_list, mail_inbox_read, mail_folder_list, mail_search, mail_thread, mail_move, mail_mark, mail_attachment_get, mail_reply. Test count 27 -> 33: 2 for MarkAction::parse (alias coverage + unknown rejection), 4 for tools::extract_addr (display-name strip + bare-addr passthrough + garbage tolerance + ToField unwrap).		2026-05-21 08:42:39 -07:00
crates/mail-mcp	Phase C: mail_mark, mail_attachment_get, mail_reply	2026-05-21 08:42:39 -07:00
.gitignore	mail-mcp v0.1 — Rust MCP server for Sulkta email	2026-05-21 06:50:25 -07:00
Cargo.lock	mail-mcp v0.1 — Rust MCP server for Sulkta email	2026-05-21 06:50:25 -07:00
Cargo.toml	mail-mcp v0.1 — Rust MCP server for Sulkta email	2026-05-21 06:50:25 -07:00
config.example.toml	mail-mcp v0.1 — Rust MCP server for Sulkta email	2026-05-21 06:50:25 -07:00
README.md	mail-mcp v0.1 — Rust MCP server for Sulkta email	2026-05-21 06:50:25 -07:00

README.md

mail-mcp

Rust MCP server for Sulkta-hosted email. SMTP send + IMAP read with RFC-correct headers, multipart/alternative when HTML is included, multipart/mixed for attachments, threading via In-Reply-To/References.

Replaces the scripts/kayos_mail.py CLI path that lived in kayos/openclaw-workspace since 2026-04-23.

Why a server, not a CLI

kayos_mail.py shipped without Date or Message-ID headers until a 2026-05-18 patch — exactly the kind of header-discipline regression a typed Rust server prevents at compile time. The "no spam bin" framing is mostly upstream of any client (Rackham postfix + rspamd DKIM-sign at the relay; mail-tester scored 10/10 and port25 SpamAssassin −7.31 on 2026-05-20), but a correct client doesn't trip filters with bad MIME structure, broken threading, or missing headers.

Tools (v0.1)

mail_send — send mail. Args: account?, to, cc[]?, bcc[]?, subject, body, body_html?, attachments[]?, in_reply_to?, references[]?. Returns {message_id, sent_at}.
mail_inbox_list — list folder messages newest-first. Args: account?, since? (YYYY-MM-DD), unread_only?, limit? (default 50, max 500), folder? (default INBOX). Uses BODY.PEEK so it does not toggle \Seen.
mail_inbox_read — fetch one message by UID. Args: account?, uid, folder?, format? (text|html|raw_eml). Attachment payloads are not inlined — only filename/mime_type/size metadata.

Headers we guarantee on outbound

Date — UTC, RFC 5322 (lettre auto)
Message-ID — <UUIDv4@<from_addr_domain>> — own-domain, never the container hostname
From — name <addr>
MIME-Version: 1.0
User-Agent: mail-mcp/<version>
In-Reply-To + References when threading args present
Content-Type correct for the body shape (text-only / alternative / mixed)

DKIM-Signature is applied by the relay (rspamd on Rackham), not the client.

Build

cargo build --release

Binary lands at target/release/mail-mcp.

Config

mkdir -p ~/.config/mail-mcp
cp config.example.toml ~/.config/mail-mcp/config.toml
chmod 600 ~/.config/mail-mcp/config.toml

Edit accounts as needed. Passwords are NEVER inline:

Looked up from the env var named in password_env
Falling back to password_file (shell-format: KEY=VALUE per line)
Hard-failing with a vault-pointer hint if neither resolves

Vault canonical: bw.sulkta.com → kayos@sulkta.com — IMAP/SMTP.

MCP wiring (Claude Code / kayos-house)

{
  "mcpServers": {
    "mail-mcp": {
      "command": "/usr/local/bin/mail-mcp",
      "args": []
    }
  }
}

Logging is stderr-only — stdout is the JSON-RPC transport.

Future phases

Phase B (~200 LOC): multi-account routing across all configured [accounts.*], plus mail_thread and mail_search.
Phase C (~150 LOC): mail_mark (read/unread/flag/trash/archive), mail_attachment_get, mail_reply helper.

Full locked spec: kayos/openclaw-workspace → memory/spec-mail-mcp.md.

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