Facebook has announced an update to its in-house Messages application that will seamlessly integrate email, Facebook messages, SMS, IM, and Facebook Chat. The product will include a full conversation history from all the mediums, and a social inbox which filters messages according to what a user wants to see.

Last week, we speculated that Facebook would be refining how users sort the messages they receive.

It will take all the communication between two people, regardless of medium, and show it in one thread. Users will have an @facebook.com email address with their public vanity URL as the prefix. However, the new Messages will look more like Chat, with messages added to threads in real-time and the option to instantly reply. “Our goal is for it to feel like a conversation” says Director of Engineering Andrew Bosworth, “people should share however they want to share.”

Product Details

Regardless of where the message is delivered, it will appear in the thread which notifications lead back to. Users can trigger through the interface whether they want the message to be sent to a specific medium of a friend, such as SMS to their phone. Otherwise, it will be routed automatically. For instance, if a user is online when they’re sent a message, they’ll receive it as a Chat.

Users will have the option to forward select messages from a thread to another user, one of the most requested features for Messages. They can also be added or removed from threads to join or leave a conversation.

By default, you’ll only see messages from friends and friends of friends in your primary inbox. The “Other Messages” view will show users what they don’t care as much about, including Event messages. Senders can be moved between these two inboxes. Facebook expects users will constantly check their main folder, and occasionally check their Other Messages.

While users can’t “go off the record” while messaging, they’ll be able to permanently archive or delete threads. File attachments can be sent, and IMAP will be supported soon.

Underlying Technology, Security, and Privacy

To implement the new system, Facebook built a new storage system called hBase, and started a fifteen engineer team, the biggest for any new Facebook product. Facebook is shifting away from the Cassandra storage system it built.

As for security, instead of relying on a “security by obscurity” method of inbox privacy, users will have control of who can send them messages. They can change their privacy settings to bounce back messages from those they don’t want to receive messages from.

The product will be rolled out over the next few months, starting with an invite system.

CEO Mark Zuckerberg says this is not a Gmail killer, and that Facebook doesn’t expect people to immediately switch all their email to the product.