Previous studies have shown that pre-editing techniques can handle the extreme variability and uneven quality of user-generated content (UGC), improve its machine-translatability and reduce post-editing time. Nevertheless, it seems important to find out whether real users of online communities, which is the real life scenario targeted by the ACCEPT project, are linguistically competent and willing to pre-edit their texts according to specific pre-editing rules. We report the findings from a user study with real French-speaking forum users who were asked to apply pre-editing rules to forum posts using a specific forum plugin. We analyse the interaction of users with pre-editing rules and evaluate the impact of the users' pre-edited versions on translation, as the ultimate goal of the ACCEPT project is to facilitate sharing of knowledge between different language communities.