A short while ago, my wife received two seemingly identical catalogues in the post from a well-known online fashion retailer. Both were addressed to our home, but the catalogues differed in two respects. Firstly, one was labelled using her maiden name, whilst the other used her married surname. The second difference was more interesting. The first catalogue promised a 30% reduction on all purchases as a loyal customer reward. The second catalogue promised a 20% reduction. This told me two important things: (1) my wife spends more with this retailer since we married; (2) the retailer in question has no master data management (MDM) strategy for addresses.