Unreplied allows you to see all of those missed conversations and makes it super simple to get back into them. Unreplied lives in your Mac's status bar and updates itself periodically. You have an assortment of filtering options at your disposal to make sure that only the important messages get through.
Unreplied is also really secure: it uses the macOS sandbox to keep all of your conversations confidential and inaccessible to other apps or services. The sandbox blocks network and file system access so Unreplied can't share your data even if it wanted to!