As crowdsourcing gains popularity, organisations seek ways to systematically and reliably involve their workforce with data processing pipelines. Mobile crowdsourcing allows for opportunistic task executions and thus, potentially, for higher throughput. However, how to engage and to retain employees in enterprise crowdsourcing campaigns is still an open research topic. .is paper discusses the results of a study performed in IBM Benelux. We surveyed 93 employees to discover the factors that might a.ect engagement in mobile enterprise crowdsourcing. .e survey informed the design of an experiment that aimed at investigating the e.ectiveness of di.erent task noti€cation strategies. We studied how factors such as time and context of noti€cation can a.ect the participation and retention of employees. Results show that break times are the most suitable for crowd work, and that "aggressive" noti€cation strategies act as deterrent for participation, while moderate yet regular nudges are the most likely to retain contributors.@en