Software Gems: The Computer History Museum Historical Source Code Series

Electronic mail is one of “killer apps” of networked computing. The ability to quickly send and receive messages without having to be online at the same time created a new form of human communication. By now billions of people have used email.

Email has a long and storied history, dating back to MIT’s Compatible Time Sharing System (CTSS) and the US government’s AUTODIN in the early 1960s. These early systems, which often used propriety communications networks and protocols, were generally incompatible with each other; you could only exchange mail with people using the same system.

The first email on the ARPANET (the predecessor of today’s internet) was sent by Ray Tomlinson in 1971, and mail formats became standardized (RFC 524, RFC 561) soon thereafter. In the 1980s, the Post Office Protocol for TCP/IP codified the communication between email clients (which run on the user’s computer) and the email server (where messages are received from other systems and stored), so that there could be independent implementations of both on different computers and operating systems.

Eventually many email clients were written for personal computers, but few became as successful as Eudora. Available both for the IBM PC and the Apple Macintosh, in its heyday Eudora had tens of millions of happy users. Eudora was elegant, fast, feature-rich, and could cope with mail repositories containing hundreds of thousands of messages. In my opinion it was the finest email client ever written, and it has yet to be surpassed.

I still use it today, but, alas, the last version of Eudora was released in 2006. It may not be long for this world. With thanks to Qualcomm, we are pleased to release the Eudora source code for its historical interest, and with the faint hope that it might be resuscitated. I will muse more about that later.