# block_sender

Block an email address (e.g. spammer@evil.com) or entire domain (e.g. @evil.com). Max 50 per mailbox.

Agent View of the PolicyLayer registry record for `block_sender`. HTML page: https://policylayer.com/tools/trekmail-mcp-server/block-sender

## Facts

- Tool: `block_sender`
- Server: TrekMail MCP Server (`trekmail/mcp-server`) — https://policylayer.com/tools/trekmail-mcp-server.md
- Homepage: https://github.com/trekmail/mcp-server
- Risk category: Write (Medium risk)
- Registry record: grade F, identity unverified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Rate-limited

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "block_sender",
    "arguments": {}
  }
}
```

## Why block_sender is rated Medium

This tool modifies email filtering configuration by creating block rules, which is a reversible write operation. The effect is not destructive (rules can be unblocked), nor does it execute arbitrary code or move financial assets. While blocking senders affects email delivery behavior, the action itself is a configuration write that persists blocking metadata.

From the tool's own definition: "Tool description states 'Block an email address or entire domain' which creates a blocking rule that modifies mailbox configuration settings."

Risk signals: Bulk/mass operation — affects multiple targets

## Use case

AI agents use block_sender to create or update resources in TrekMail MCP Server, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your TrekMail MCP Server environment.

## Recommended policy (PolicyLayer)

Verdict: **Rate-limited**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches TrekMail MCP Server:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "block_sender": {
      "limits": [
        {
          "counter": "block_sender_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}
```

## Other tools on TrekMail MCP Server (247)

- `bulk_action` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/bulk-action.md
- `cancel_bulk_migration` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/cancel-bulk-migration.md
- `cancel_migration` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/cancel-migration.md
- `cancel_scheduled` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/cancel-scheduled.md
- `change_mailbox_password` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/change-mailbox-password.md
- `confirm_delete_intent` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/confirm-delete-intent.md
- `create_delete_intent` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/create-delete-intent.md
- `delete_alias` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/delete-alias.md
- `delete_bulk_migration` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/delete-bulk-migration.md
- `delete_calendar_event` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/delete-calendar-event.md
- `delete_cloudflare_token` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/delete-cloudflare-token.md
- `delete_contact` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/delete-contact.md
- `delete_contact_group` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/delete-contact-group.md
- `delete_domain` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/delete-domain.md
- `delete_domain_smtp_profile` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/delete-domain-smtp-profile.md
- `delete_external_account` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/delete-external-account.md
- `delete_folder` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/delete-folder.md
- `delete_forwarding_address` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/delete-forwarding-address.md
- `delete_identity` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/delete-identity.md
- `delete_mail_rule` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/delete-mail-rule.md
- `delete_message` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/delete-message.md
- `delete_migration` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/delete-migration.md
- `delete_smtp_connection` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/delete-smtp-connection.md
- `delete_template` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/delete-template.md
- `drive_bulk_purge` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/drive-bulk-purge.md
- `drive_bulk_trash` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/drive-bulk-trash.md
- `drive_device_revoke` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/drive-device-revoke.md
- `drive_file_purge` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/drive-file-purge.md
- `drive_file_trash` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/drive-file-trash.md
- `drive_folder_purge` — Destructive — https://policylayer.com/tools/trekmail-mcp-server/drive-folder-purge.md
- …and 217 more: https://policylayer.com/tools/trekmail-mcp-server.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

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Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=trekmail-mcp-server · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/trekmail-mcp-server