CLAUDE DUET

Give Claude Duet
its own inbox.

Add Mermail as a custom connector on claude.ai. Duet uses it from your Claude account.

Why Claude Duet

Built for the agent you already use.

Duet works in the background from Anthropic’s cloud. Mermail gives it a mailbox it owns for signups, vendor replies, and receipts, so your personal inbox stays out of its errands.

Remote MCP connector with OAuth, added once on claude.ai

Duet reuses the connector from your Claude account

A hosted address for Duet’s own signups and follow-ups

Duet asks before it sends email for you

Before you start

Check 3 things.

A US Claude Pro or Max plan with Duet access from the waitlist.

Claude on the web, desktop, or mobile to add the connector.

You can sign in to the intended Mermail workspace.

Introducing Claude Duet

Success contract

Done when all 3 pass.

Mermail shows Connected under Settings → Connectors.

list_mailboxes succeeds in a Claude chat.

Duet answers the same request with your mailboxes.

Three steps to connect.

Add a custom connector on claude.ai

Settings → Connectors → Add custom connector. Name it Mermail, paste this URL, and leave Advanced settings empty.

Remote MCP URL · OAuth

https://console.mermail.app/mcp

Connect with OAuth

Select Connect, sign in to Mermail, and choose the workspace Duet should use. Add no API key or headers.

Test in Claude, then in Duet

Enable Mermail in a new Claude chat and run this read-only check. Then send the same request in Duet.

Verify

List my Mermail mailboxes using list_mailboxes.

Working prompt

Give Duet a standing job.

Paste this in Duet after setup. Replace YOUR_EMAIL with an inbox you can check.

Prompt

Use my hosted Mermail mailbox as your own email address. List mailboxes first and create one only if none is suitable. Send a short test to YOUR_EMAIL and tell me the From address. From now on, include new mail in that mailbox in my daily brief, and ask me before you send anything.

Recipes

Copy a job into chat.

Paste any prompt into Claude Duet after you connect MCP. Use a separate chat for a long-running job. Claude Duet asks for approval where your permission settings require it.

Signups

Sign up as itself

Duet registers with its hosted address and reads its own verification code.

Prompt

Use your hosted Mermail mailbox to sign up for the service I named. Check that mailbox for the verification email right away, read the code, and finish signup. Do not use my Gmail.

What happens. The code lands in Duet’s mailbox, not yours.

Daily brief

Brief from its own inbox

Replies to Duet’s errands show up in your morning brief.

Prompt

Each time you prepare my daily brief, check your Mermail mailbox. List replies that need my decision, quotes that arrived, and threads waiting longer than three days.

What happens. One brief covers everything Duet is chasing.

Outreach

Collect quotes

Vendors reply to Duet, not to your personal address.

Prompt

From your Mermail mailbox, email the five vendors I listed for a quote. Show me each draft before sending. Track the replies and compare price, timing, and terms once three have answered.

What happens. Each vendor stays in one thread on Duet’s mailbox.

Errands

Chase a refund

The follow-up you keep putting off.

Prompt

I’m forwarding my order confirmation to your Mermail address. Ask the store’s support team for a refund from that mailbox, follow up every two days, and tell me when they reply.

What happens. The back-and-forth lives in Duet’s mailbox until you need to act.