Raindrop 0.1 is still very much in its infancy, but will allow users to filter their inbox so that the most pressing emails are brought to immediate attention and those from mailing lists are sidelined.
"Email was overloaded even before it became the place for all these web services to send you updates, and we've been looking at this problem to make email personal again," said a Mozilla spokesman in a promotional video. "Why should an advert from an airline push a message from my mum out of the way?"
The company said that the platform will connect web users' different email accounts, and integrate messages from contacts on social networking sites.
The social networking messages will also be categorised so that '@replies' and direct messages from Twitter, for example, will appear in a separate view.
Finally, Raindrop will allow users to view YouTube and Flickr links directly in their inbox rather than having to launch a separate web browser.
The application will work with the Firefox, Safari and Chrome browsers, and Mozilla has released an application programming interface that will help developers create systems that can be used with Raindrop.
"We hope to lead and spur the development of extensible applications that help users easily and enjoyably manage their conversations, notifications and messages across a variety of online services," said the company.
Commentators have suggested that Raindrop is Mozilla's version of Google Wave.