The Midnight Memo

A sealed envelope was found slipped under the door of the editor-in-chief's office. Inside was a single folded note bearing a short encoded message. Security footage shows four staff members still in the building when the note was delivered.

The rules

1. Four people in this building are known to write coded notes. Each has a different cipher style.
2. Six clues describe their habits and one important property of the note itself.
3. Use the clues to decode the message and name the encoder.
4. One submission. You can’t change your answer.