Q.W.K.
The QWK format is used the world over by millions of people daily to help them manage their e-mail.

Before the QWK format was invented, users would be forced to call a bulletin board system (a BBS) and read each message online.
Reading messages online limited the amount of information a user could receive from a BBS.
If they were calling the BBS via a long distance connection, then the user was also running up huge telephone bills too.
Finally, when a user was reading messages online, other users could not use the BBS.

All of this changed in 1987 with the introduction of the QWK format by Sparkware, a method to read and write messages off-line...