Question: Is there a Google Sheets extension that can help me clean up email lists and generate placeholder data?

If you want to scrub your email lists and then use a Google Sheets extension to generate placeholder data, GPT Workspace is a great option. It automates Google Sheets tasks, including categorizing and summarizing data, which can help you get your data in order. And it's free, with no limits, so it's easy to get started.

Another option is ManyExcel. It generates formulas, regex patterns and scripts for Google Sheets and Excel that you can use to automate data cleaning and placeholder generation. It's got a free tier with limited use, and a Pro tier for more advanced abilities, so you can use it depending on your needs and budget.

If you want to focus on Google Sheets, SheetAI offers AI-powered functions to automate repetitive tasks and generate new insights. It's got features like AI-generated lists and tables, and magic fills to rapidly fill in data, which can dramatically speed up your productivity and workflow.

Last, Numerous.ai brings ChatGPT right into Google Sheets and Excel, with a simple setup and syntax that's easy to use. It works with teams and can handle lots of tasks, including summarizing and categorizing data, so it's a good choice for your data wrangling needs.