diff --git a/src/NServiceBus.AcceptanceTests/Core/DependencyInjection/When_endpoint_is_warmed_up.cs b/src/NServiceBus.AcceptanceTests/Core/DependencyInjection/When_endpoint_is_warmed_up.cs
index b2c4b545fc..aa9733ae0d 100644
--- a/src/NServiceBus.AcceptanceTests/Core/DependencyInjection/When_endpoint_is_warmed_up.cs
+++ b/src/NServiceBus.AcceptanceTests/Core/DependencyInjection/When_endpoint_is_warmed_up.cs
@@ -115,7 +115,7 @@ class SpyContainer : IServiceProvider, IServiceScopeFactory
             public SpyContainer(IServiceCollection serviceCollection)
             {
                 foreach (var serviceDescriptor in serviceCollection
-                    .Where(sd => sd.ServiceType.Assembly == typeof(IMessage).Assembly))
+                    .Where(sd => sd.ServiceType.Assembly == typeof(EndpointConfiguration).Assembly))
                 {
                     RegisteredServices[serviceDescriptor.ServiceType] = new RegisteredService
                     {
diff --git a/src/NServiceBus.Core.Analyzer.Tests.Common/Helpers/AnalyzerTestFixture.cs b/src/NServiceBus.Core.Analyzer.Tests.Common/Helpers/AnalyzerTestFixture.cs
index b98dffcce2..fb8fb5ea58 100644
--- a/src/NServiceBus.Core.Analyzer.Tests.Common/Helpers/AnalyzerTestFixture.cs
+++ b/src/NServiceBus.Core.Analyzer.Tests.Common/Helpers/AnalyzerTestFixture.cs
@@ -114,6 +114,7 @@ static AnalyzerTestFixture()
                 MetadataReference.CreateFromFile(Assembly.Load("System.Private.CoreLib").Location),
 #endif
                 MetadataReference.CreateFromFile(typeof(EndpointConfiguration).GetTypeInfo().Assembly.Location),
+                MetadataReference.CreateFromFile(typeof(IMessage).GetTypeInfo().Assembly.Location),
                 MetadataReference.CreateFromFile(typeof(IUniformSession).GetTypeInfo().Assembly.Location));
         }
 
diff --git a/src/NServiceBus.Core.Tests/API/Infra/NServiceBusAssembly.cs b/src/NServiceBus.Core.Tests/API/Infra/NServiceBusAssembly.cs
index c286a6d921..867f9a7c12 100644
--- a/src/NServiceBus.Core.Tests/API/Infra/NServiceBusAssembly.cs
+++ b/src/NServiceBus.Core.Tests/API/Infra/NServiceBusAssembly.cs
@@ -6,7 +6,7 @@
 
     static class NServiceBusAssembly
     {
-        public static readonly List<Type> Types = typeof(IMessage).Assembly.GetTypes()
+        public static readonly List<Type> Types = typeof(EndpointConfiguration).Assembly.GetTypes()
             .Where(type => !type.IsObsolete())
             .ToList();
     }
diff --git a/src/NServiceBus.Core.Tests/API/NullableAnnotations.cs b/src/NServiceBus.Core.Tests/API/NullableAnnotations.cs
index d3b0755388..000c88e5e8 100644
--- a/src/NServiceBus.Core.Tests/API/NullableAnnotations.cs
+++ b/src/NServiceBus.Core.Tests/API/NullableAnnotations.cs
@@ -52,7 +52,7 @@ bool HasNonAnnotatedMember(Type type)
         {
             foreach (var member in type.GetMembers())
             {
-                if (member.DeclaringType.Assembly != typeof(IMessage).Assembly)
+                if (member.DeclaringType.Assembly != typeof(EndpointConfiguration).Assembly)
                 {
                     continue;
                 }
diff --git a/src/NServiceBus.Core.Tests/ApprovalFiles/APIApprovals.ApproveNServiceBus.approved.txt b/src/NServiceBus.Core.Tests/ApprovalFiles/APIApprovals.ApproveNServiceBus.approved.txt
index 12bd14ee08..cd90ea1714 100644
--- a/src/NServiceBus.Core.Tests/ApprovalFiles/APIApprovals.ApproveNServiceBus.approved.txt
+++ b/src/NServiceBus.Core.Tests/ApprovalFiles/APIApprovals.ApproveNServiceBus.approved.txt
@@ -476,7 +476,6 @@ namespace NServiceBus
     {
         System.Threading.CancellationToken CancellationToken { get; }
     }
-    public interface ICommand : NServiceBus.IMessage { }
     public interface IConfigureHowToFindSagaWithMessage
     {
         void ConfigureMapping<TSagaEntity, TMessage>(System.Linq.Expressions.Expression<System.Func<TSagaEntity, object?>> sagaEntityProperty, System.Linq.Expressions.Expression<System.Func<TMessage, object?>> messageProperty)
@@ -517,7 +516,6 @@ namespace NServiceBus
     {
         System.Threading.Tasks.Task Stop(System.Threading.CancellationToken cancellationToken = default);
     }
-    public interface IEvent : NServiceBus.IMessage { }
     public interface IHandleMessages<T>
     {
         System.Threading.Tasks.Task Handle(T message, NServiceBus.IMessageHandlerContext context);
@@ -526,7 +524,6 @@ namespace NServiceBus
     {
         System.Threading.Tasks.Task Timeout(T state, NServiceBus.IMessageHandlerContext context);
     }
-    public interface IMessage { }
     public interface IMessageConvention
     {
         string Name { get; }
diff --git a/src/NServiceBus.Core.Tests/RedirectHelper.cs b/src/NServiceBus.Core.Tests/RedirectHelper.cs
index fd726c0dc6..76f16781c1 100644
--- a/src/NServiceBus.Core.Tests/RedirectHelper.cs
+++ b/src/NServiceBus.Core.Tests/RedirectHelper.cs
@@ -17,7 +17,7 @@ static Assembly CurrentDomain_AssemblyResolve(object sender, ResolveEventArgs ar
     {
         if (args.Name.StartsWith("NServiceBus.Core,"))
         {
-            return typeof(IMessage).Assembly;
+            return typeof(EndpointConfiguration).Assembly;
         }
         return null;
     }
diff --git a/src/NServiceBus.Core/ICommand.cs b/src/NServiceBus.Core/ICommand.cs
index 893545427b..af739dd156 100644
--- a/src/NServiceBus.Core/ICommand.cs
+++ b/src/NServiceBus.Core/ICommand.cs
@@ -1,9 +1,4 @@
-namespace NServiceBus
-{
-    /// <summary>
-    /// Marker interface to indicate that a class is a command message.
-    /// </summary>
-    public interface ICommand : IMessage
-    {
-    }
-}
\ No newline at end of file
+using System.Runtime.CompilerServices;
+using NServiceBus;
+
+[assembly: TypeForwardedTo(typeof(ICommand))]
\ No newline at end of file
diff --git a/src/NServiceBus.Core/IEvent.cs b/src/NServiceBus.Core/IEvent.cs
index a91c801b90..1e167cb292 100644
--- a/src/NServiceBus.Core/IEvent.cs
+++ b/src/NServiceBus.Core/IEvent.cs
@@ -1,9 +1,4 @@
-namespace NServiceBus
-{
-    /// <summary>
-    /// Marker interface to indicate that a class is a event message.
-    /// </summary>
-    public interface IEvent : IMessage
-    {
-    }
-}
\ No newline at end of file
+using System.Runtime.CompilerServices;
+using NServiceBus;
+
+[assembly: TypeForwardedTo(typeof(IEvent))]
\ No newline at end of file
diff --git a/src/NServiceBus.Core/IMessage.cs b/src/NServiceBus.Core/IMessage.cs
index 8f1e1a7aa0..850f4773f6 100644
--- a/src/NServiceBus.Core/IMessage.cs
+++ b/src/NServiceBus.Core/IMessage.cs
@@ -1,10 +1,4 @@
-namespace NServiceBus
-{
-    /// <summary>
-    /// Marker interface to indicate that a class is a message suitable
-    /// for transmission and handling by an NServiceBus.
-    /// </summary>
-    public interface IMessage
-    {
-    }
-}
\ No newline at end of file
+using System.Runtime.CompilerServices;
+using NServiceBus;
+
+[assembly: TypeForwardedTo(typeof(IMessage))]
\ No newline at end of file
diff --git a/src/NServiceBus.Core/NServiceBus.Core.csproj b/src/NServiceBus.Core/NServiceBus.Core.csproj
index da33480763..fd70f9ce02 100644
--- a/src/NServiceBus.Core/NServiceBus.Core.csproj
+++ b/src/NServiceBus.Core/NServiceBus.Core.csproj
@@ -21,6 +21,8 @@
     <PackageReference Include="System.Diagnostics.DiagnosticSource" Version="7.0.2" />
     <PackageReference Include="System.Security.Cryptography.Xml" Version="7.0.1" />
     <PackageReference Include="System.Text.Json" Version="7.0.3" />
+    <!-- Would be a package dependency to 1.0.0 in real life -->
+    <Projectreference Include="..\NServiceBus.MessageAbstractions\NServiceBus.MessageAbstractions.csproj" />
   </ItemGroup>
 
   <ItemGroup Label="Private dependencies">
diff --git a/src/NServiceBus.MessageAbstractions/ICommand.cs b/src/NServiceBus.MessageAbstractions/ICommand.cs
new file mode 100644
index 0000000000..893545427b
--- /dev/null
+++ b/src/NServiceBus.MessageAbstractions/ICommand.cs
@@ -0,0 +1,9 @@
+namespace NServiceBus
+{
+    /// <summary>
+    /// Marker interface to indicate that a class is a command message.
+    /// </summary>
+    public interface ICommand : IMessage
+    {
+    }
+}
\ No newline at end of file
diff --git a/src/NServiceBus.MessageAbstractions/IEvent.cs b/src/NServiceBus.MessageAbstractions/IEvent.cs
new file mode 100644
index 0000000000..a91c801b90
--- /dev/null
+++ b/src/NServiceBus.MessageAbstractions/IEvent.cs
@@ -0,0 +1,9 @@
+namespace NServiceBus
+{
+    /// <summary>
+    /// Marker interface to indicate that a class is a event message.
+    /// </summary>
+    public interface IEvent : IMessage
+    {
+    }
+}
\ No newline at end of file
diff --git a/src/NServiceBus.MessageAbstractions/IMessage.cs b/src/NServiceBus.MessageAbstractions/IMessage.cs
new file mode 100644
index 0000000000..8f1e1a7aa0
--- /dev/null
+++ b/src/NServiceBus.MessageAbstractions/IMessage.cs
@@ -0,0 +1,10 @@
+namespace NServiceBus
+{
+    /// <summary>
+    /// Marker interface to indicate that a class is a message suitable
+    /// for transmission and handling by an NServiceBus.
+    /// </summary>
+    public interface IMessage
+    {
+    }
+}
\ No newline at end of file
diff --git a/src/NServiceBus.MessageAbstractions/NServiceBus.MessageAbstractions.csproj b/src/NServiceBus.MessageAbstractions/NServiceBus.MessageAbstractions.csproj
new file mode 100644
index 0000000000..edd49243f7
--- /dev/null
+++ b/src/NServiceBus.MessageAbstractions/NServiceBus.MessageAbstractions.csproj
@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netstandard2.0</TargetFramework>
+    <SignAssembly>true</SignAssembly>
+    <AssemblyOriginatorKeyFile>..\NServiceBus.snk</AssemblyOriginatorKeyFile>
+  </PropertyGroup>
+
+  <ItemGroup Label="Private dependencies">
+    <PackageReference Include="Particular.Packaging" Version="3.0.0" PrivateAssets="All" />
+  </ItemGroup>
+
+</Project>
diff --git a/src/NServiceBus.TransportTests/NServiceBusTransportTest.cs b/src/NServiceBus.TransportTests/NServiceBusTransportTest.cs
index ee7afdb36e..c06f409fee 100644
--- a/src/NServiceBus.TransportTests/NServiceBusTransportTest.cs
+++ b/src/NServiceBus.TransportTests/NServiceBusTransportTest.cs
@@ -39,7 +39,7 @@ protected static IConfigureTransportInfrastructure CreateConfigurer()
 
             if (string.IsNullOrWhiteSpace(transportToUse))
             {
-                var coreAssembly = typeof(IMessage).Assembly;
+                var coreAssembly = typeof(EndpointConfiguration).Assembly;
 
                 var nonCoreTransport = transportDefinitions.Value.FirstOrDefault(t => t.Assembly != coreAssembly);
 
diff --git a/src/NServiceBus.sln b/src/NServiceBus.sln
index 70332477f7..eb1b7c43ea 100644
--- a/src/NServiceBus.sln
+++ b/src/NServiceBus.sln
@@ -40,6 +40,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "NServiceBus.Learning.Accept
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "NServiceBus.Core.Analyzer.Tests.Roslyn4", "NServiceBus.Core.Analyzer.Tests.Roslyn4\NServiceBus.Core.Analyzer.Tests.Roslyn4.csproj", "{71330321-DA6D-4199-89C4-FB36F92E77C2}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "NServiceBus.MessageAbstractions", "NServiceBus.MessageAbstractions\NServiceBus.MessageAbstractions.csproj", "{9BF4758C-DC80-4D91-87DA-623B8FA20CAA}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -94,6 +96,10 @@ Global
 		{71330321-DA6D-4199-89C4-FB36F92E77C2}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{71330321-DA6D-4199-89C4-FB36F92E77C2}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{71330321-DA6D-4199-89C4-FB36F92E77C2}.Release|Any CPU.Build.0 = Release|Any CPU
+		{9BF4758C-DC80-4D91-87DA-623B8FA20CAA}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{9BF4758C-DC80-4D91-87DA-623B8FA20CAA}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{9BF4758C-DC80-4D91-87DA-623B8FA20CAA}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{9BF4758C-DC80-4D91-87DA-623B8FA20CAA}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE