In Aha! - users only receive emails as a watcher, commenter, or via a To Do. Feature Due Dates are an important part of a created feature, and users should be receiving emails (similar to To Dos) when Feature Due Dates are upcoming, present, or overdue.
Thank you for the idea. Since this idea was submitted we have added new capabilities for tracking delivery risks. It is currently possible to set automatic delivery risks based on feature due dates. You can then build reports using this information. We hope that helps make it easier to keep track of features approaching, or past, their due dates. You can learn about delivery risks here: https://www.aha.io/support/roadmaps/strategic-roadmaps/customizations/manage-at-risk-work
Given the capabilities with delivery risks, we do not have plans to add notifications as this idea suggests. We hope you can understand.