Competitor email monitoring, inside ChatGPT, Claude and your browser.
Ask Signal where you already work.
Signal by StackEnhance is a free, read-only connector for AI assistants and a Chrome extension. It answers from the same public archive as the brand pages: how often a store sends marketing e-mail, what it sent recently and which stores email most in a market. No account, nothing to install on a server.
Add Signal to ChatGPT, Claude or Chrome
ChatGPT
Add the Signal app once; ChatGPT calls it when a question is about a brand’s e-mail. Open in ChatGPT’s app directory →
By hand: Settings → Apps & Connectors → Advanced → Developer mode → Create, name it Signal by StackEnhance, paste the connector URL below, no authentication.
Claude
Connect from Claude’s directory and ask in any chat, on web, desktop or mobile. Open in Claude’s directory →
By hand: Settings → Connectors → Add custom connector, name it Signal by StackEnhance, paste the connector URL below, leave the OAuth fields empty.
Chrome extension
On any online store, click the icon: last send, e-mails per week, recent subjects. Sites are matched on your device.
Install from the Chrome Web Store → · How the extension works →
One MCP server URL for every AI client
Signal is a standard MCP server. Paste the address into any assistant or coding tool that speaks the protocol and it gains three tools: brand e-mail frequency, brand summary and most active senders. Nothing to install, no key to manage.
Connector URL: https://mcp.stackenhance.com/mcp (Streamable HTTP · No login · Read-only · Free)
Quick start
- Copy the URL The address above is all a client needs.
- Add it as an MCP server In ChatGPT, Claude, Cursor, VS Code or Claude Code: Settings → connectors or MCP → add, paste, save.
- Ask “How often does Lindex email in Sweden?” The assistant calls Signal and cites the brand page.
Paste-ready for your client
Claude Code
In the terminal. Run the command once; the tools are available in every session.
claude mcp add --transport http signal https://mcp.stackenhance.com/mcpCursor and Windsurf
Settings → MCP → Add server. Paste the snippet, or add a server named signal with the URL.
{
"mcpServers": {
"signal": { "url": "https://mcp.stackenhance.com/mcp" }
}
}VS Code with GitHub Copilot
Agent mode. Add to .vscode/mcp.json (or user settings → MCP), then start the server from the editor.
{
"servers": {
"signal": { "type": "http", "url": "https://mcp.stackenhance.com/mcp" }
}
}Gemini CLI
Google’s terminal assistant. Add to ~/.gemini/settings.json. The Gemini API and SDKs take the same URL as an MCP tool.
{
"mcpServers": {
"signal": { "httpUrl": "https://mcp.stackenhance.com/mcp" }
}
}What it answers: email frequency, send days, top senders
- How many marketing e-mails a brand sent in a period, and the average per week.
- The dates it sent on, for periods of up to a month.
- Up to two subject lines per answer, only ones already shown on the brand’s public page.
- Which brands send the most in a market (Sweden, Norway, Denmark, Finland, Germany), by category.
- Every answer cites the brand’s page on stackenhance.com as the source.
What it does not
- Periods start within the last six months. Older history, year-over-year and full campaign archives are in a Signal account.
- No open, click or revenue data: Signal observes the e-mails brands send, nothing about recipients.
- No campaigns, offers, products or creative analysis through the connector. That is Signal itself.
- The connector stores no conversation text and no identifiers; a request is logged as tool, brand, market and outcome.
Questions to try in ChatGPT or Claude
- How often does IKEA email its customers in Sweden?
- What did Rusta send last week?
- Which home-interior brands email most in Denmark?
- Compare how often Mio and Westwing emailed in September.
Questions
Is there a free competitor email monitoring tool for ChatGPT?
Yes, this one. Signal by StackEnhance is a free app in ChatGPT’s directory and a free connector in Claude’s. Ask how often a competitor emails, what it sent last week or who emails most in your market, and the answer cites the brand’s public page.
Is it free?
Yes. The connector, the Chrome extension and the public brand pages are free and need no account. A Signal account adds the campaigns themselves, scores, calendar, compare and alerts.
Which brands can it answer about?
The online stores Signal follows: thousands in Sweden, Norway, Denmark, Finland and Germany. If a store is missing, the Chrome extension lets you ask us to track it with one click; only the site name is sent.
Does it work in Gemini, Grok or Perplexity?
Wherever those products accept an MCP server, yes: paste the connector URL. Gemini CLI and the Gemini API do; the consumer apps add connector support at their own pace, and the server works the day they do.
Why six months?
The public server is a sample of what Signal knows. Longer history and year-over-year comparisons are what a Signal account is for.
Where does the data come from?
From marketing e-mails that online stores send to Signal’s own subscriber inboxes. Counts are de-duplicated sends; welcome, birthday and transactional e-mails are excluded.