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Mailshake API and MCP server

Mailshake's API cannot reply to a lead, add a follow-up to a campaign or move leads between campaigns. Sign in to Mailshake once in your own Cloud Browser, and your AI agent does the work there for you. The same tools work over MCP for agents and as a REST API for scripts.

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Mailshake has no API for this. So we run one for you.

Mailshake's own API, a GitHub MCP server and Cotlet compared
What you need Mailshake's APIGitHub MCP serverCotlet
Lead replies, follow-ups, lead moves No Partly Yes, 15 tools
Acts as you, signed in 24/7 No No Yes, Cloud Browser
Fixed for you when Mailshake changes N/A No Yes, tested every 6h
Runs with your laptop off N/A No Yes, hosted

Checked Oct 22, 2026. Sources: Mailshake API reference · Mailshake Help: API Limits · Mailshake Help: How do I reply to a lead? · Zapier: Mailshake integrations

Your own Cloud Browser, on 24/7. Sign in once. We keep it connected.

  1. 01Sign in to Mailshake in your own Cloud Browser

  2. 02Connect it for your agents

  3. 03Cotlet keeps it signed in and working

How do I connect Mailshake to Claude, ChatGPT or my code?

AI agents connect over MCP, scripts call the REST API. Both reach the same 15 tools with one API key.

For AI agents: MCP

Add Cotlet to your agent once. Mailshake and every other app you connect show up as its tools.

  • Claude
  • ChatGPT
  • OpenClaw
  • Hermes
  • GrokBot
  • Cursor
  • n8n
  • Any MCP client
  1. 1

    Add Cotlet to your agent

    Claude Code
    claude mcp add --transport http cotlet \
  https://cotlet.dev/mcp/v1 \
  --header "Authorization: Bearer $COTLET_API_KEY"
    Cursor
    {
  "mcpServers": {
    "cotlet": {
      "url": "https://cotlet.dev/mcp/v1",
      "headers": {
        "Authorization": "Bearer ${COTLET_API_KEY}"
      }
    }
  }
}
    Codex
    # ~/.codex/config.toml
[mcp_servers.cotlet]
url = "https://cotlet.dev/mcp/v1"
bearer_token_env_var = "COTLET_API_KEY"

    Paste the snippet for your client. The same server and key serve every app you connect, so you do this once.

For scripts: REST API

Every tool is an endpoint under /api/v1/mailshake with its own method and path, such as POST /api/v1/mailshake/campaigns/{campaign_id}/recipients, with the same API key. Our open-source repo has ready scripts to start from.

REST API docs

What can the Mailshake API and MCP server do?

15 tools on your own Mailshake account. Agents call them as operations of the MCP tools mailshake_read and mailshake_write; scripts call each one at its own REST endpoint, with the same inputs and answers.

API reference
Mailshake tools in Cotlet's MCP server and REST API
Tool What it does Access
list_campaigns Your team's campaigns with title, state, sender and number of emails in the sequence. read
get_campaign One campaign with its message sequence: initial email, follow-ups, drips and on-click emails. read
list_recipients Recipients of a campaign, searchable and filterable by what they did. read
list_replies Most recent replies, bounces, out-of-office notes and unsubscribes with the message text. read
list_leads Leads from Lead Catcher with status, campaign, recipient and who they are assigned to. read
add_recipients Add people to a campaign with a name and custom fields for the text replacements in your emails. writeasks first
pause_campaign Stop all sending for a campaign right away. write
resume_campaign Start sending again for a paused campaign. writeasks first
pause_recipient Stop or restart the emails of one recipient in one campaign and keep the rest of the campaign running. write
unsubscribe_recipients Add email addresses to your team's unsubscribe list so no campaign emails them again. writeasks first
update_lead_status Mark a lead won, lost or ignored, or open it again. write
assign_lead Give an open lead to a teammate, or set it to unassigned so anyone can take it. write
reply_to_lead Send an email reply to a lead from Lead Catcher, as you would with the Reply button. writeasks first
move_leads_to_campaign Add leads to another campaign, as the Add to Campaign action in Lead Catcher does. writeasks first
add_follow_up Add a follow-up email at the end of a campaign's sequence, with a delay after the previous email. writeasks first

Scroll the table for all 15 tools.

Ask in plain words. Your agent does the rest.

All Mailshake use cases

Is it safe to connect Mailshake?

You sign in yourself in your own Cloud Browser, we never save your password, and anything that reaches your readers waits for your OK. The browser profile is encrypted in the EU. Independent scanners grade cotlet.dev A+.

Security overview

How much do the Mailshake API and MCP server cost?

One price for both: a tool call costs the same over MCP or REST. Free 7-day trial with 2,000 credits, no card needed. Then one-time credit packs, no subscription, valid 12 months. Most calls use 25 credits, and your Cloud Browser uses 50 credits a day while Mailshake is enabled for agents, so 20 calls a day come to 550 credits.

See full pricing
Cotlet credit packs: price, credits and calls at 25 credits each
Credits Price, one time Calls at 25 credits Per 1,000 credits
5,000 $29 200 $5.80
15,000 $79 600 $5.27
32,000 $149 1,280 $4.66
60,000 $249 2,400 $4.15

Only successful calls use credits; failed calls and timeouts cost nothing. At a balance of 0 calls pause, never a surprise charge. Authenticate with the Authorization: Bearer header.

Questions

Does Mailshake have an API?

Yes, Mailshake has a REST API for campaigns, recipients, leads and activity, with an API key from Integrations > API, but no official MCP server (checked 22 Oct 2026). The API cannot send a reply from Lead Catcher, add a follow-up to a campaign, move leads between campaigns or assign a lead.

How do I get access?

Sign up free, open Mailshake under Integrations in the console and press Request access. Your free trial starts with your account, no card needed.

Is the MCP server different from the API?

No, only the way in. Cotlet builds each integration as a REST API and puts an MCP server on top, so both have the same 15 tools, the same inputs and answers, one API key and one price. AI agents such as Claude, ChatGPT or Cursor use MCP; scripts, cron jobs and HTTP steps in n8n, Make or Zapier use the REST API.

What is the Cloud Browser?

Your own Chrome that Cotlet runs for you in the EU, around the clock. You open it from the console, sign in to Mailshake yourself and press Enable for agents. Your agent's calls go through it, from its IP with its cookies, so Mailshake sees the browser you signed in with. Password saving is off and the profile is stored encrypted with AES-256-GCM.

Can my agent act without asking me?

Not on anything that reaches other people: add_recipients, resume_campaign, unsubscribe_recipients, reply_to_lead, move_leads_to_campaign, add_follow_up wait for your OK by default. You can switch that off per tool for scheduled runs.

Do I need a Mailshake API key or a certain plan?

No key. Cotlet works in your signed-in Mailshake account and does not use the API. Mailshake does not tie its API to one plan in its help center: limits for API calls per hour and for recipients added per month depend on your plan and grow with each user seat.

How many recipients can a campaign hold?

Mailshake's API reference says up to 5,000 recipients per campaign. Its help center gives 5,000 prospects on the Email Outreach plan and 10,000 on Sales Engagement. add_recipients lists the addresses that did not fit in over_campaign_limit_emails.

Should I use a Mailshake MCP server from GitHub instead?

Pick one if you want the code on your own computer and do not mind the upkeep: you install it, sign it in and fix it when Mailshake changes. Pick Cotlet if you want it hosted and kept working for you.

Can I use it in n8n, Make or Zapier?

Yes. Add https://cotlet.dev/mcp/v1 in n8n's MCP Client node, or call the REST endpoints from an HTTP step in Make or Zapier.

Who runs Cotlet?

Cotlet is run by Take Group, a Polish software company working since 2019. Take Group runs about 3,200 websites on its own systems and has its own DevOps team for infrastructure security. We built and used integrations like this inside the company for years before opening them as Cotlet.

Is Cotlet affiliated with Mailshake?

No. Cotlet is independent and not affiliated with Mailshake.

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