Link a domain mailbox to Grok for customer mail

They used a custom mailbox plus a webhook so Grok Bot could handle incoming customer messages from their own domain.

Done with Grok Bot· Intermediate· Oct 2026

What they did
The poster wanted to move beyond Grok’s built-in mail setup for customer communication, so they set up a mailbox on a domain they control and exposed it to Grok through an MCP connector. Since new messages would not automatically start any action, they added a webhook that launches a Grok automation whenever a fresh email arrives. They found that the webhook only worked when requests used Grok’s signed whsec_ secret style; bearer-token requests were rejected.
How it went
The setup gave them a customer email identity under their own domain and direct access to the mailbox, while Grok still handled responses when mail came in. They said Grok’s default mail is fine for signups and verification codes, but all bots share the same address, there is no inbox view, and nothing fires automatically.
Tips
Use signed webhook requests from the outset, since bearer-token calls produced 400s for them. Keep a human check in the loop until you are confident a message category is safe to automate.

Try it yourself with Grok Bot

Connect Grok Bot to [address@mydomain.com] so it can manage incoming customer email for my business. For each new message, identify the type of request, consult [system/docs] for any relevant details, and write a reply in my style. Present the draft to me and stop until I approve it before you send, delete, submit, or make any other irreversible change. If I later tell you a category is safe to automate, ask me before turning that category on for automatic sending.

Fill in the [brackets]. Agents can make mistakes, so review anything before it is sent, paid or deleted.

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