Comment by ChrisMarshallNY

It was basically before Internet email.

Proprietary store-and-forward system, run by a BT subsidiary, named Dialcom. Ran on Prime minicomputers.

I worked there in 1987.

[UPDATED TO ADD] And to add insult to injury, it was all on sub-VGA 300-Baud VT-100 terminals and line printers.

I spent a lot of time, staring at blue-striped paper.