We've improved how Buttondown handles undeliverable subscribers:
- Added detailed undeliverability reasons to help you understand why specific subscribers can't receive emails
- New filtering options in the subscribers list to find subscribers by undeliverability status and reason
- API support for retrieving and filtering by undeliverability data
- Improved internal tracking to better identify potentially problematic email addresses
This helps you maintain a cleaner list and provides more insight into delivery problems before they affect your sending reputation.