Postage Due is an original composition by Caity Gyorgy, written prior to 2020 and first recorded as the opening track of her debut album No Bounds, released in April of that year with her quartet. The tune is an upbeat, swinging number with a tightly arranged melody that gives way to an open solo section where the full ensemble locks in. The arrangement features solo spots for multiple band members, reflecting Gyorgy's skill at writing parts that spotlight individual musicians while maintaining group cohesion.
The song draws on a deeply personal inspiration. Its opening lyric, referencing penny loafers, originated from a real conversation between Gyorgy and her grandmother Hilary about 1950s fashion and the practical habit of keeping a coin in one's shoe for payphone calls. The composition weaves together nostalgic imagery of penny loafers, payphones, and handwritten letters, the last detail drawn from the many letters Gyorgy has received from her grandmother over the years. Critics have noted that Gyorgy's musicality and emotional sincerity shine through most clearly on her own compositions, with Postage Due frequently cited as a standout example of her ability to balance technical craft with genuine sentiment.