GMass API Documentation & MCP Config | Salestools Club
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Sales Engagement

GMass

Powerful mail merge and cold email system for Gmail.

Connect with AI
Give docs to Claude
Public API
Available
MCP
Not available
Free tier
Available

How to connect

Give docs to Claude
Open API docs

What your agent can do

01Gmail Outreach Automation
02Automated Follow-up Sequences
03Lead Verification
04Cold Email Outreach
05Sales Automation

Connect GMass

01Open the API docsGive the REST documentation to Claude Code or Cursor.
02AuthenticateConfigure API Key without pasting secrets into chat.
03Build the first workflowUse the starter prompt below as a brief for your coding agent.
Open API documentation

Starter prompt

Claude, use GMass to send a mail merge campaign to this list of leads and set up 3 automated follow-ups for non-repliers.

About GMass

GMass provides an API for programmatically managing cold email campaigns, follow-ups, and lead lists directly within the Gmail ecosystem. It is a popular tool for sales reps and individual outbounders who want to leverage Gmail's deliverability while using powerful automation features. The API enables the creation of automated sequences, lead verification, and synchronization of campaign results.