It is well documented that people would remunerate fair behaviours and penalize unfair behaviours. It is argued that individuals' reactions following the receipt of a gift depend on the perceived intentions of the donors. Fair intentions should prompt positive affect, like gratitude, triggering cooperative behaviours; while intended unfairness should trigger negative affect, like anger, fostering anti-social actions. It is, however, contended that when people lack information to infer others' intention they may use 'normative' beliefs about fairness - what a typical fair individual 'should' do in these circumstances - to guide their behaviour. In this experiment we examined this assertion. We had 122 participants play a one-shot, double-anonymous game with half playing as potential helpers (P1s) and half as recipients (P2s). Whether a participant was a P1 or P2 was chance-determined and all participants knew this. P1s decided whether to help P2s and whether to make their help unconditional (no repayment needed) or conditional (full or 'taxed' repayment). P2s decided whether to accept the offer and whatever conditions attached but were blind to the list of helping options available to P1s. We anticipated that recipients would refer to the 'injunctive norm' that 'fair people should help "for free" when it is only by chance that they are in a position to help'. Therefore, without knowing P1s' different helping options, unconditional offers should be rated by recipients as fairer than conditional offers, and this should be linked to greater gratitude with greater gratitude linked to greater reciprocation. Path analyses confirmed this serial mediation. The results showed that recipients of unconditional offers, compared to conditional ones, interpreted the helpers' motives as more helpful, experienced greater gratitude and were more eager to reciprocate. The behavioural data further revealed that, when given a latter option to default, 38% of recipients of conditional offers did so.