The plaintext is a telegram. That means that it is composed only of letters, with no symbols. Numerals (if any) have to be spelled out, and take up a lot of space. Divisions between sentences are marked with the word "STOP," which might therefore occur frequently. The message will end with "END OF MESSAGE."
WARNING: This cryptogram contains at least one "fixed point". These are letters of plaintext that encrypt to themselves as ciphertext. (For example, J encrypts as J, or something like that.)
A joint project of Brendan Bard, Prof. Gregory Bard, and Prof. Seth Dutter, University of Wisconsin---Stout (January 30th, 2019)