Product Owner - Do you know how to build/update the backlog?

Do not use emails as you can't order them by the business priorities.

Use Azure DevOps (E.g. https://ssw.visualstudio.com) as it allows you to enter an item into the backlog, in the preferred priority order.

✅ Figure: Good Example - Azure DevOps allows you to enter an item into the backlog, in any priority order

Note: You can also create a PBI using Azure DevOps and attach an email directly if needed, without using Team Companion