Electronic mail (email) evolved from traditional postal systems and telegraph communication. Ray Tomlinson is credited with inventing email in 1971 when he sent the first message containing the text "QWERTYUIOP" between two computers. Email works through an interaction between mail user agents, mail delivery agents, and mail transport agents that allow users to send and receive messages via protocols like SMTP, POP3, and IMAP running on port numbers 25, 110, and 143, respectively.

1. Electronic Mail
(Email)

2. Evolution of Mailing
Electronic mail
(Email)
Telegraph
Snail mail
• By horse or by
foot
• Postal
• Morse Code
• Facsimile
(Fax)
Reference: Overnight Prints (2013)

3. Invention
Inventor: Ray Tomlinson in late 1971
First message sent:
“QWERTYUIOP”
Designation: @ symbol to separate the
user’s login name and the host
computer
Reference: Duffy (2003) ; Brain & Crosby (2013);
Bellis (2013)

4. How Email Works?

5. Mail User Agent
Mail Delivery Agent
Mail Transport Agent
Reference: Kavi Help Center

6. Mail Servers
Simple Mail Transfer Protocol (SMTP)
 handle the sending
 TCP Port 25
Post Office Protocol (POP3)
 Retrieving emails & leaving a copy on the server (in some
cases)
 TCP Port 110
Internet Mail Access Protocol (IMAP)
 Coordinating the status of emails (read, deleted, moved)
 TCP Port 143

8. References
Bellis, M. (2013). HIstory of Email & Ray Tomlinson. About.com Inventors. Retrieved
from http://inventors.about.com/od/estartinventions/a/email.htm.
Brain, M. & Crosby, T. (2013). How E-mail Works. howstuffworks.com. Retrieved from
http://computer.howstuffworks.com/e-mail-messaging/email.htm.
Duffy, D. (2003, September 8). Ray Tomlinson: Inventor of e-mail. Darwin Magazine.
Retrieved from http://hr-system.com/email,%20how%20Ray%20Tomlinson%20invented@.pdf.
Kavi Help Center. (2013). How Email Really Works. In Kavi Help Center, Kavi Mailing
List Manager Help. Retrieved from https://www.oasisopen.org/khelp/kmlm/user_help/html/how_email_works.html.
Overnight Prints. (2013). The History of Mail: From Traditional to Electronic. Retrieved
from http://www.overnightprints.com/history-of-mail.