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Use this how-to to connect an Atlassian site to hosted Sendmux MCP. You need Atlassian organisation administrator access and a Sendmux user who can approve the intended team, product surfaces, and mailboxes. This page does not cover local servers, private HTTP, or Atlassian’s built-in system integrations.

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Add the server

1

Open connected apps

In Atlassian administration, open Apps > Sites, select the site, and open Connected apps.
2

Choose a custom MCP server

Open the dropdown beside Explore apps, choose Add external MCP server, then choose Custom MCP server.
3

Enter the connection details

Enter MCP URL as https://mcp.sendmux.ai/mcp, MCP server name as Sendmux, and Authentication as OAuth. The hosted endpoint uses Streamable HTTP and OAuth 2.1 authorisation code with PKCE and dynamic client registration (DCR). You do not need a manually created Sendmux client ID or secret.
4

Authorise the grant

Complete Sendmux browser authorisation. Select only the team, product surfaces, and mailboxes needed for this connection.
5

Verify the connection

Confirm Sendmux appears in Connected apps and its tools appear. Invoke one read-only connection or list tool from a granted surface. This verifies your configuration: it does not automatically certify Atlassian as a client.
See Atlassian’s external MCP server setup procedure for the administration workflow.

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Manage tools

Open Apps > Sites, select the site, then open Connected apps > Actions > View app details > Tools selection. Deselect a tool to deactivate it. Sendmux mutations remain governed by the selected grant and each tool’s behaviour. See Atlassian’s external MCP tool configuration guide.
Uninstalling the external server removes its tools for all users and breaks workflows that depend on them. Deactivate individual tools when you need a narrower change.
See Atlassian’s external MCP server removal guidance before uninstalling.

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Troubleshoot invalid_target

OAuth keeps four boundaries separate: a registration can restrict an exact resource, an authorisation request asks for a resource, the approved grant binds that resource, and the access token carries the same audience. Omitting resource during DCR creates no registration restriction. If a later authorisation, code-exchange, or refresh request omits the resource, only that later REST request defaults to https://sendmux.ai/api. For hosted MCP, invalid_target means the requested resource does not match an explicitly restricted registration or is not an exact supported resource. Confirm MCP URL is exactly https://mcp.sendmux.ai/mcp and Authentication is OAuth. Do not reuse a REST or A2A registration, broaden an existing restriction, weaken resource checks, change scopes, or uninstall and re-add the server as a workaround. If the documented configuration still fails, record the non-secret error and request identifier and contact Sendmux support. Do not include tokens or capability URLs.

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Next steps

MCP client setup

Compare documented hosted, local, and private HTTP configurations.

MCP overview

Review hosted grants, product surfaces, and connection modes.