Just upgraded to the latest Aspose.Email.dll .Net 2.0, (Aug 6, 2015) from the older version Dec 31, 2014. It is saying your dll is relying on an indirect reference to four .Net 3 assemblies and will not compile in a .Net 2.0 app.
25>C:\Windows\Microsoft.NET\Framework\v4.0.30319\Microsoft.Common.targets(1605,5): warning MSB3268: The primary reference “Aspose.Email, Version=2.0.0.0, Culture=neutral, PublicKeyToken=ad504e9f0d34714a, processorArchitecture=MSIL” could not be resolved because it has an indirect dependency on the framework assembly “PresentationCore, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35” which could not be resolved in the currently targeted framework. “.NETFramework,Version=v2.0”. To resolve this problem, either remove the reference “Aspose.Email, Version=2.0.0.0, Culture=neutral, PublicKeyToken=ad504e9f0d34714a, processorArchitecture=MSIL” or retarget your application to a framework version which contains “PresentationCore, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35”.
25>C:\Windows\Microsoft.NET\Framework\v4.0.30319\Microsoft.Common.targets(1605,5): warning MSB3268: The primary reference “Aspose.Email, Version=2.0.0.0, Culture=neutral, PublicKeyToken=ad504e9f0d34714a, processorArchitecture=MSIL” could not be resolved because it has an indirect dependency on the framework assembly “WindowsBase, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35” which could not be resolved in the currently targeted framework. “.NETFramework,Version=v2.0”. To resolve this problem, either remove the reference “Aspose.Email, Version=2.0.0.0, Culture=neutral, PublicKeyToken=ad504e9f0d34714a, processorArchitecture=MSIL” or retarget your application to a framework version which contains “WindowsBase, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35”.
25>C:\Windows\Microsoft.NET\Framework\v4.0.30319\Microsoft.Common.targets(1605,5): warning MSB3268: The primary reference “Aspose.Email, Version=2.0.0.0, Culture=neutral, PublicKeyToken=ad504e9f0d34714a, processorArchitecture=MSIL” could not be resolved because it has an indirect dependency on the framework assembly “UIAutomationProvider, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35” which could not be resolved in the currently targeted framework. “.NETFramework,Version=v2.0”. To resolve this problem, either remove the reference “Aspose.Email, Version=2.0.0.0, Culture=neutral, PublicKeyToken=ad504e9f0d34714a, processorArchitecture=MSIL” or retarget your application to a framework version which contains “UIAutomationProvider, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35”.
25>C:\Windows\Microsoft.NET\Framework\v4.0.30319\Microsoft.Common.targets(1605,5): warning MSB3268: The primary reference “Aspose.Email, Version=2.0.0.0, Culture=neutral, PublicKeyToken=ad504e9f0d34714a, processorArchitecture=MSIL” could not be resolved because it has an indirect dependency on the framework assembly “UIAutomationTypes, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35” which could not be resolved in the currently targeted framework. “.NETFramework,Version=v2.0”. To resolve this problem, either remove the reference “Aspose.Email, Version=2.0.0.0, Culture=neutral, PublicKeyToken=ad504e9f0d34714a, processorArchitecture=MSIL” or retarget your application to a framework version which contains “UIAutomationTypes, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35”.