SeaMonkey (Internet Suite)★★★☆☆The old Mozilla Suite lives on! Featuring web, email, news, an HTML editor, IRC client and more. Recent work has mostly been to keep it working and backport security fixes, so web app compatibility lags way behind even the ESR Firefox.
Gmail on SeaMonkeyYes, you can still connect it after the switch to OAuth2. You need to create a placeholder account first, and find the right settings, which Gmail doesn’t seem to tell you anymore.