Fastmail MCP Server

Instructions

Implementation Reference

• src/index.ts:420-433 (registration)

  Registration of the 'delete_email' tool including its input schema in the MCP server's listTools response.
  { name: 'delete_email', description: 'Delete an email (move to trash)', inputSchema: { type: 'object', properties: { emailId: { type: 'string', description: 'ID of the email to delete', }, }, required: ['emailId'], }, },
• src/index.ts:936-951 (handler)

  MCP server handler for the 'delete_email' tool: extracts emailId, initializes JmapClient, calls deleteEmail, and returns success message.
  case 'delete_email': { const { emailId } = args as any; if (!emailId) { throw new McpError(ErrorCode.InvalidParams, 'emailId is required'); } const client = initializeClient(); await client.deleteEmail(emailId); return { content: [ { type: 'text', text: 'Email deleted successfully (moved to trash)', }, ], }; }
• src/jmap-client.ts:362-396 (handler)

  Core implementation in JmapClient: finds trash mailbox, constructs JMAP Email/set request to move the email by updating its mailboxIds, executes via makeRequest.
  async deleteEmail(emailId: string): Promise<void> { const session = await this.getSession(); // Find the trash mailbox const mailboxes = await this.getMailboxes(); const trashMailbox = mailboxes.find(mb => mb.role === 'trash') || mailboxes.find(mb => mb.name.toLowerCase().includes('trash')); if (!trashMailbox) { throw new Error('Could not find Trash mailbox'); } const trashMailboxIds: Record<string, boolean> = {}; trashMailboxIds[trashMailbox.id] = true; const request: JmapRequest = { using: ['urn:ietf:params:jmap:core', 'urn:ietf:params:jmap:mail'], methodCalls: [ ['Email/set', { accountId: session.accountId, update: { [emailId]: { mailboxIds: trashMailboxIds } } }, 'moveToTrash'] ] }; const response = await this.makeRequest(request); const result = response.methodResponses[0][1]; if (result.notUpdated && result.notUpdated[emailId]) { throw new Error('Failed to delete email.'); } }