This study describes an experiment to discover difference between system novice and expert performance of a web-based email system, but in addition also the dimension of user experience with test evaluations as well. For this purpose a longitudinal laboratory based usability evaluation and a "snapshot" evaluation of a web-based email system was conducted. Both the numbers of different types of identified problems and the severity of the problems are investigated. The study shows that after only a period of two months of system experience the number of usability problems decreased signifiantly. The study also shows that experience with tests did not caused users to identify significant different usability problems compared to inexperienced test subjects.