Proofy

Proofy screens lists to identify and separate addresses into five categories: valid, invalid, disposable, duplicate, and catch-all. The duplicate detection is especially useful if you're consolidating lists from multiple sources or managing signup data across different campaigns and don't want to oversend to the same person.

It's built for marketers doing quarterly list maintenance and working with multiple data sources. The duplicate and catch-all categories help you optimize send frequency and targeting while the clear categorization lets you decide which addresses to keep, suppress, or revisit later.