There is a growing interest in exploring the potential benefits and risks of digital work communication (DWC) for employers and employees. While some studies view the use of DWC as a demand that threatens employees’ mental health, others regard it as a resource that provides health benefits. The empirical evidence has been ambiguous, offering support for both assumptions but with limited explanations. Our study contributes to the ongoing discourse by examining the extent of DWC and the advantages and disadvantages associated with its use, including positive (increased flexibility) and negative (a lack of flexibility, the need to be constantly available, overload, and loss of personal contact) perceptions. Using a sample of 4,422 employees in 160 German work organisations, we conducted moderation and mediation analyses in structural equation modelling and found that more DWC was associated with poorer mental health. Although both negative and positive perceptions were directly related to mental health, they also moderated and mediated the relationship between the DWC and mental health. In conclusion, our research demonstrated that it is not the use of DWC alone that is harmful to mental health, but rather its intensity and the circumstances in which it is used.