The advent of the modern Post Office was when Sir Rowland Hill consolidated the various existing private postal services into the National Penny Post in London in 1840.
He established a network of post offices, sorting offices and postal routes that, by and large, is still in use today. His system of International and regional sorting offices routing mail to local postal offices is very similar to the Internet network organization supporting email send and receive. The first non-paper based mail services came into being a few years later when the electric telegraph service used Morse Code to transmit messages over wires, and later over wireless connections.
The next major advance in text-based message systems was the development in the 1930s of the Telex system as a network of teleprinters connected to a dedicated network. The International Telecommunication Union assured universal acceptance by defining standards that provided the first common protocols for international message communications. By using equipment that conformed to these standards, customers on any telex exchange could deliver messages to any other around the world. Telex is still in use today. The development of electronic computers as we know them today was given a major boost during World War 2. All the combatants were using sophisticated systems to encode their radio transmissions. Bothe UK and the US worked hard to develop decoding techniques and the UK in particular at Bletchley Park used electromechanical and electronic methods to decode transmissions. Their "Colossus" machine significantly reduced the time taken to decode messages.
The earliest general-purpose stored-program electronic digital computer to work was built in the Royal Society Computing Machine Laboratory at Manchester University in the UK. The Manchester 'Baby', as it became known and performed its first calculation on 21 June 1948. It is alleged that the lights in Manchester dimmed when it was switched on.
A commercial version of the machine became the world's first commercially available computer, the Ferranti Mark I. The first to be completed was installed at Manchester University in February 1951. Finally, about ten were sold in Britain, Canada, Holland, and Italy. In the US it was Pennsylvania University who developed ENIAC and announced it in 1946 as the first true electronic computer. They started developments in 1943 to create a machine that could calculate artillery firing tables. Other manufacturers jumped on the computing bandwagon, including IBM. Thomas J. Watson, their Chairman, foresaw a market of 9 or 10 computers worldwide. As we know he was a wee bit off the mark, even in the 1950s.
Email as we understand it now started on single mainframe computers in the mid-1960s. At that time computers were not linked to each other and users used dumb terminals to run applications on the mainframe. The first email applications were really simple local file sharing, where users deposited text messages in an email folder owned by the recipient.
Early mail programs were SNDMSG and MAILBOX. Email was therefore limited to users on the same computer.
We waited for the development of local and remote networking and interconnection of computers before the next big step. As with so many developments, the net big step came courtesy of the military. The US Government were running a major development program, ARPANET, which later morphed into the Internet as we see it now.
Networking computers meant the post problem became a little more complex - a message needed to go into an envelope, addressed and sent. The recipient need not be on the same computer anymore. So, the first matter was to locate and uniquely identify the recipient as with paper mail (now becoming known as snail mail).
ARPANET and Ray Tomlinson fixed that. Ray Tomlinson defined email addresses to be user@computer. Something we still use today. With this "nice hack" as Jan Postel described it, we were good to go with a massive expansion of networked email. The first universal email systems were based on the existing paper mail systems and were in effect a store-and-forward system using the Post Office Protocol3 ("PoP3") and Simple Mail Transfer Protocol ("SMTP") standards. Using the Tomlinson address structure, networking software would use SMTP software to forward the message to the receiving computer where the PoP3 software would receive the message for the recipient. The steps in between were handled by standard networking techniques. That ability was dependent on the development of the Internet, the arteries along which the email travels and the development of email exchanges, which like paper postal services, route the email to its final destination.
Despite whatever else might happen on the Internet, email is still the biggest thing. Over 2600 million users currently use email. The arrival of PCs in the 1980s gave another big boost to email. One of the biggest costs associated with email was the cost of connection to the mail server where the user's email was stored, and "Offline Readers" rapidly developed.
Microsoft Outlook is a good example. What offline readers provided was the ability to connect the PC to the mail server, download incoming email and upload outgoing email and then go offline again. The user could then read inward emails and compose replies at their leisure without incurring connection charges. This is still very common today.
The next development was the Internet Mail Access Protocol ("IMAP"). The IMAP protocol provided a mechanism for manipulating mail directly on the mail server from a desktop program without the need to download it. You obviously need to be connected, so this was mainly used by corporate users with a continuous connection to the Internet. It is only with the rollout of ADSL and Fibre connections to the home that users are starting to use IMAP. The latest development is cloud-based email, where the email stays on the Internet. Prime examples are Windows Hotmail, Google Gmail, and other branded online mail services provided by commercial organizations and Internet Service Providers.
The biggest advantage of IMAP and cloud-based email is that of accessibility. Because the user is manipulating email on the server, and not on a file store on a fixed desktop, the user can use a variety of different methods to read and respond to email from any location. The email store is available from an IMAP client on any desktop and from web-based apps on smartphones and tablets anywhere. The biggest threat to email is smartphone messaging apps like Twitter and Whatsapp.
However, while these apps are restricted in the size of the message that can be sent and the platforms on which they operate, they are likely to be perceived as instant messaging apps and not true email clients.
Email will endure.