"I wrote many novels which … contained the element of the projected collective unconscious, which made them simply incomprehensible to anyone who read them, because they required the reader to accept my premise that each of us lives in a unique world."
- Philip K. Dick

Simeon Kenton, of Kenton Space Enterprises, Unlimited, was in a terrible temper... His mildly whiskered saint's visage was screwed up into unutterable knots. In his tight-clutched fingers was a blue spacegram which he shook violently at his daughter at each choking pause in his peroration...

('Jurisdiction' by Nat Schachner)

Old Simeon glared at her and waved the offending spacegram so violently it ripped in his fingers.

Here's another use, from Off the Beam (1944) by George O. Smith:

A steward found Channing in the salon and handed him a ’gram. Channing smiled, and the steward returned the smile and added : “You’ll fix these ships to talk back one day. Wait until you read that one — you’ll burn from here to Terra !”

"Reading my mail?" asked Channing cheerfully. The average spacegram was about as secret as a postcard, so Channing didn't mind...