In inkjet printing for mailing, the diverse range of available envelope papers poses significant challenges for reliable readability of printed barcodes. If not properly controlled, ink/media interactions, in particular ink sorption, can result in unacceptable degradation in print quality, directly affecting machine readability. Several commercially available aqueous inkjet inks and several recycled and regular envelopes were tested by conventional methods and by ultrasonic attenuation. In this case study, we printed a selected set of envelope papers at low speed (office inkjet printing) with carefully designed test patterns and performed a statistical analysis to correlate print quality attributes and machine readability. Print quality attributes were measured according to ISO-13660 definitions, which are well suited for automated measurement. To elucidate the correlation between paper characteristics and print quality attributes, sorption measurements were also obtained on the same set of envelope papers. Machine readability data were obtained from a verifier reading AIM print quality parameters from DataMatrix symbols. The results of the case study not only provide insight into the correlation between print quality attributes and machine readability but also demonstrate the practical value of implementing ISO-13660 in barcode print quality.