In tip 4138, Microsoft described how to request Remote Assistance by sending E-mail.
Microsoft Knowledge Base Article 306791 contains the following summary:
This step-by-step article describes how to provide help by using the Remote Assistance feature in Windows XP in response to an e-mail invitation. Remote Assistance enables you to establish a connection to a remote computer through the Internet. This connection can be used to view the computer screen, participate in real-time chat, and remotely control that computer (when you have permission to do so).