According to Deckbox rules:
3.2 Neutral Feedback does not affect a user's Percentile, and is to be used at a user's discretion. However, it is strongly suggested that users submit a neutral rating to any transaction that suffers from two or more 'bad trading practices,' including but not limited to:
Rude or aggressive behavior
Exceptionally poor communication
Tardiness in shipping without notice
Insufficient protection of goods
Misrepresentation of goods3.3 Negative feedback may only be left with staff approval. Users desiring to leave negative feedback must file a Bad Trading Report. Users leaving negative feedback without staff approval will be sanctioned. Negative feedback will generally be approved for the following reasons:
Scamming and attempts to rip users off
Refusing / Ignoring to answer deckbox staff or moderators on trade issues and Bad Trading Report resolutions
Lying about when cards were sent or received, or about card conditions
Backing out of a confirmed trade and refusing to renegotiate a compensatory trade
In this particular case, neutral feedback should suffice as your trade partner did not violate any rules that warrants negative feedback. The purpose of considering trades confirmed after addresses have been exchanged is to help prevent traders from sending their cards prematurely.
There have been BTRs filed where traders have cancelled the trade even after addresses were confirmed. As long as no cards were sent by either party, the Deckbox Team will generally only permit positive or neutral feedback. This is because there is no loss on either side - except for time, which can be marked appropriately by leaving neutral feedback.