MCP server
Connect your AI assistant to Lettermint to inspect email activity, check delivery and DNS, and perform controlled actions. Lettermint hosts the MCP server, so you do not need to install or run a local service.
Code
Quickstart
You need a verified Lettermint account and at least one team where MCP access is enabled. Your client must support remote Streamable HTTP servers and OAuth.
Use OAuth to connect. Project API tokens and Team API tokens do not work with the hosted MCP server.
Choose your AI client. Cursor users can also add Lettermint in one click.
Code
Your client opens a browser. Sign in to Lettermint, review the connection, and approve access.
Test the connection with: “Use Lettermint to list my teams and projects. Do not send an email.”
What your assistant can do
Lettermint provides a selected set of tools instead of a generic API executor.
| Area | Available tools |
|---|---|
| Documentation | search_documentation |
| Teams and projects | list_teams, list_projects, get_project |
| Email activity | search_messages, get_message, list_message_events, get_message_content |
| Delivery and usage | get_delivery_stats, get_team_usage |
| Routes and domains | list_routes, get_route, list_domains, get_domain, verify_domain_dns, verify_inbound_domain |
| Webhooks | list_webhooks, get_webhook, list_webhook_deliveries |
| Suppressions | search_suppressions, add_suppression |
| Sending | send_email |
Your current role and project assignment determine which tools can run. Reading message metadata and reading message content are separate permissions.
Access and safety
- The OAuth connection belongs to you, not to one team.
- Lettermint checks your account, team membership, project access, role, and team settings on every call.
- Teams filter personal information returned through MCP by default. While filtering is enabled, message content, sending, and suppression changes are not available.
- Message content follows the normal 28-day data retention policy.
- The MCP server cannot manage API tokens, members, roles, billing, or project settings. It never returns webhook signing secrets.
- Sending is limited to one message per call and requires an idempotency key.
See Roles and Project access for the permissions that apply.
MCP actions are real. An assistant can send email, start domain verification, verify an inbound domain, or add a suppression when your permissions and team settings allow it. Review sensitive actions before you approve them.
Try these prompts
- “List the Lettermint teams and projects I can access.”
- “Summarize delivery statistics for this project over the last seven days.”
- “Find failed messages from today and explain their delivery events.”
- “Check the DNS verification status for this sending domain.”
- “Show recent webhook deliveries that failed.”
- “Search the Lettermint documentation for sending domains and DKIM.”
Manage access
Open User settings → Applications to review or revoke a connection. Revoking a connection invalidates its access across all teams.
A member with Manage team security can open Manage team → Settings to disable MCP access or change personal-information filtering for a team.
Troubleshooting
| Problem | What to check |
|---|---|
| The sign-in page is unavailable | Confirm that your account is active and verified and that at least one team allows MCP access. |
| A team or project is missing | Check your team membership, project assignment, and the team's Allow MCP access setting. |
| A tool returns a permission error | Check your role. A new connection does not change your permissions. |
| The client needs authentication | Start the client's MCP sign-in action again. For example, run codex mcp login lettermint or select Lettermint from /mcp. |
| Sending is denied | Check personal-information filtering, sender verification, team status, quota, spend limits, and suppressions. |
An OAuth token cannot call /v1 or /rest/v1 | This is expected. MCP OAuth tokens work only with the hosted MCP server. |
Related documentation
Roles
Review the permissions that MCP follows.
Project access
Control which projects a team member can use.
Email activity
Search messages and understand delivery events.
Account and team security
Review account and team security controls.