OpenAI's GPT-3 can be used to write email responses for businesses, eliminating the need to manually craft emails. Zapier allows users to create automated workflows called Zaps that use GPT-3 to generate email responses. To set up this workflow, users must first connect their Gmail account and OpenAI account to Zapier, then create a Zap that triggers on new emails from customers or leads. The Zap will pull in data from the email, such as the sender's address, and use it to generate three different business email responses using GPT-3. The user can then select their preferred response and save it as a draft in Gmail. This process allows businesses to quickly respond to customer inquiries while maintaining a professional tone.