A bunch of ex-Skypers are back with Fleep, an app that brings together email, instant messaging and an alternative to existing corporate social networks in a smart way.

The experience won’t be alien to people who’ve used major corporate or personal email platforms. You can sign in via your Google account, then you start a new conversation by adding people, a subject line, a message and attachments and hitting send. So far, so familiar.

But the difference is the person included in the conversation can be another Fleep user or anyone with an email address. And Fleep has made sure it covers the major platforms people will want to use: it’s on iOS and Android as well as the desktop (Windows, Mac and browser).

Other useful features are the ability to search conversations and pin messages you might want to reference later.

The app also keeps your files under a separate tab. Now, Windows Phone is only missing piece of the puzzle.