Hi,
Yes, the namespaces of API have been updated for improved namespace structure and we have been telling our users about this change for the past three releases. You can find more information about this in our blog post [here](https://blog.aspose.com/2016/12/26/aspose.email-.net-improved-namespace-structure-available-now/). For further details about old namespace and corresponding new namespace, please refer to our documentation section [here](https://docs.aspose.com//display/emailnet/Aspose.Email+for+.NET+16.12.0+(Revamped)+Release+Notes). We hope this information will be helpful to you. Please feel free to write to us if you have any further query in this regard.