Best Alternatives to Gmail Postmaster Tools

Agent Cold Email

Runtime: npx

Agent-native cold-email infrastructure: domains, mailboxes, warmup, sequences, replies via 17 tools

Permissioned access to Gmail, Drive and Calendar via the user's own Google account

Line Bot MCP Server

Runtime: npx

Verified

Connects an AI agent to LINE Messaging API for messaging, user profiles, quotas, followers, and rich-menu management.

Google Workspace

Runtime: npx

Give AI agents access to Gmail, Calendar, Drive, and more — multi-account, manifest-driven

AI-powered medical document management for cancer patients. Google Drive, Gmail, Calendar via MCP.

Gmail

Runtime: Remote (SSE)

Allow AI systems to read, send, archive, and manage emails via Gmail.

Abnormal Security MCP

Runtime: npx

Abnormal Security email threats, cases, and reporting in your terminal and your AI agents.

Palmyr

Runtime: npx

Agent infra: email, phone, social, domains, VPS, wallets. Paid per-action via x402, no API key.

Slack MCP Server

Runtime: npx

MCP server providing Slack workspace data access with message history, threads, DMs, user info, and optional message posting.

Emailmd

Runtime: npx

Convert markdown to email-safe HTML with linting and live preview via an MCP server or local CLI.

Outlook MCP

Runtime: npx

Microsoft Outlook MCP server — 20 tools for email, calendar, contacts, and settings via Graph API.

ScopeGate

Runtime: Remote (SSE)

Granular permission gateway for MCP agents. Per-agent scopes for Google Drive, Gmail, Calendar.