With the MimeKitLite NuGet include I am no longer able to use MailKit library #542

New Issue

2025-12-29T08:29:47+01:00

adam commented

2025-12-29 08:29:47 +01:00

Originally created by @sprudel79 on GitHub (Aug 8, 2023).

Originally assigned to: @StefH on GitHub.

Describe the bug

I have just updated to latest WireMock.Net version 1.5.34 and my local project returned build errors in one of my classes where I have used MailKit (version 4.1.0) library that in itself contains "MimeKit" library.
Since WireMock.Net references "MimeKitLite" now, I got e.g. the following error:

error CS0433: The type 'MimeMessage' exists in both 'MimeKit, Version=4.1.0.0, Culture=neutral, PublicKeyToken=bede1c8a46c66814' and 'MimeKitLite, Version=4.1.0.0, Culture=neutral, PublicKeyToken=bede1c8a46c66814'

Test to reproduce

Create a sample project and add a reference

and

Now in a class try to use e.g.
var mimeMessage = new MimeMessage();

Other related info

I am using .NET 6.0.20

I could perhaps work with an alias to reference MimeKit assembly directly in my code but I would like to ask for any feedback if this is now the expected behavior or not, thank you.

Originally created by @sprudel79 on GitHub (Aug 8, 2023). Originally assigned to: @StefH on GitHub. ### Describe the bug I have just updated to latest WireMock.Net version 1.5.34 and my local project returned build errors in one of my classes where I have used MailKit (version 4.1.0) library that in itself contains "MimeKit" library. Since WireMock.Net references "MimeKitLite" now, I got e.g. the following error: **error CS0433: The type 'MimeMessage' exists in both 'MimeKit, Version=4.1.0.0, Culture=neutral, PublicKeyToken=bede1c8a46c66814' and 'MimeKitLite, Version=4.1.0.0, Culture=neutral, PublicKeyToken=bede1c8a46c66814'** ### Test to reproduce Create a sample project and add a reference <PackageReference Include="MailKit" Version="4.1.0" /> and <PackageReference Include="WireMock.Net" Version="1.5.34" /> Now in a class try to use e.g. var mimeMessage = new MimeMessage(); ### Other related info I am using .NET 6.0.20 I could perhaps work with an alias to reference MimeKit assembly directly in my code but I would like to ask for any feedback if this is now the expected behavior or not, thank you.

adam added the bug doc labels 2025-12-29 08:29:47 +01:00

adam closed this issue

2025-12-29 08:29:47 +01:00

adam commented

2025-12-29 08:29:48 +01:00

@StefH commented on GitHub (Aug 9, 2023):

@sprudel79
I understand your issue.

In the 1.5.33 version, I included the MimeKitLite as "private". However this had a side effect that the application could not work anymore.

So, please check if you use an alias.

Else I need to think on a different solution.

@StefH commented on GitHub (Aug 9, 2023): @sprudel79 I understand your issue. In the 1.5.33 version, I included the MimeKitLite as "private". However this had a side effect that the application could not work anymore. So, please check if you use an alias. Else I need to think on a different solution.

adam commented

2025-12-29 08:29:48 +01:00

@StefH commented on GitHub (Aug 10, 2023):

@sprudel79
Another option is to use WireMock.Net.Testcontainers which runs WireMock.NET inside a docker container, so it's completely separate from your unit test + source projects.

Would this be an option?

@StefH commented on GitHub (Aug 10, 2023): @sprudel79 Another option is to use [WireMock.Net.Testcontainers](https://github.com/WireMock-Net/WireMock.Net/wiki/Using-WireMock.Net.Testcontainers) which runs WireMock.NET inside a docker container, so it's completely separate from your unit test + source projects. Would this be an option?

adam commented

2025-12-29 08:29:49 +01:00

@sprudel79 commented on GitHub (Aug 10, 2023):

Thank you very much @StefH for proposing potential solutions. Indeed a docker based approach might help in this case, however it would also add more complexity to my CI/CD process. Right now I have reverted my code to use an older version of WireMock.Net and I don't have any pressure to adjust anything.
Btw. you mention version 1.5.33 which is also shown on the release page, however on nuget there's no 1.5.33 version but 1.5.34.

@sprudel79 commented on GitHub (Aug 10, 2023): Thank you very much @StefH for proposing potential solutions. Indeed a docker based approach might help in this case, however it would also add more complexity to my CI/CD process. Right now I have reverted my code to use an older version of WireMock.Net and I don't have any pressure to adjust anything. Btw. you mention version 1.5.33 which is also shown on the release page, however on nuget there's no 1.5.33 version but 1.5.34.

adam commented

2025-12-29 08:29:49 +01:00

@StefH commented on GitHub (Aug 10, 2023):

I unlisted that version because it introduced issues for users.

@StefH commented on GitHub (Aug 10, 2023): I unlisted that version because it introduced issues for users.

adam commented

2025-12-29 08:29:49 +01:00

@StefH commented on GitHub (Aug 15, 2023):

@sprudel79
Did you fix it using alias?

@StefH commented on GitHub (Aug 15, 2023): @sprudel79 Did you fix it using alias?

adam commented

2025-12-29 08:29:49 +01:00

@sprudel79 commented on GitHub (Aug 19, 2023):

Hi @StefH, I am on vacation right now and will be back on that project beginning of September...I'll let you know, thanks.

@sprudel79 commented on GitHub (Aug 19, 2023): Hi @StefH, I am on vacation right now and will be back on that project beginning of September...I'll let you know, thanks.

adam commented

2025-12-29 08:29:50 +01:00

@sprudel79 commented on GitHub (Sep 1, 2023):

Hi @StefH ,
here's the code that works:

In the csproj file I have these references:

 <PackageReference Include="MailKit" Version="4.1.0" />
 <PackageReference Include="MimeKit" Version="4.1.0">
   <Aliases>MimeKitAlias</Aliases>
 </PackageReference>
 <PackageReference Include="WireMock.Net" Version="1.5.35" />

I had to add a reference to MimeKit directly since I was not able to get things working with an alias for MailKit directly.

Next in my C# code I have these lines:

extern alias MimeKitAlias;

namespace MyNamespace
{
    public class MyClass
    {
        public void MyMethod()
        {
            var mail = new MimeKitAlias::MimeKit.MimeMessage();           
        }
    } 
}

At least I am able to build my code now without getting the error I had mentioned on top.
However, it's still cumbersome because e.g. in my VSCode environment I see

with the error:
The type or namespace name 'MimeKit' does not exist in the namespace 'MimeKitAlias', so it seems the Omnisharp C# plugin is not able to handle the alias properly and consequentially there's no intellisense anymore.
What do you think?

@sprudel79 commented on GitHub (Sep 1, 2023): Hi @StefH , here's the code that works: In the csproj file I have these references: ``` xml <PackageReference Include="MailKit" Version="4.1.0" /> <PackageReference Include="MimeKit" Version="4.1.0"> <Aliases>MimeKitAlias</Aliases> </PackageReference> <PackageReference Include="WireMock.Net" Version="1.5.35" /> ``` I had to add a reference to MimeKit directly since I was not able to get things working with an alias for MailKit directly. Next in my C# code I have these lines: ``` csharp extern alias MimeKitAlias; namespace MyNamespace { public class MyClass { public void MyMethod() { var mail = new MimeKitAlias::MimeKit.MimeMessage(); } } } ``` At least I am able to build my code now without getting the error I had mentioned on top. However, it's still cumbersome because e.g. in my VSCode environment I see ![image](https://github.com/WireMock-Net/WireMock.Net/assets/10754010/3d48f9ec-3199-450f-b104-3c9ad98c6da5) with the error: The type or namespace name 'MimeKit' does not exist in the namespace 'MimeKitAlias', so it seems the Omnisharp C# plugin is not able to handle the alias properly and consequentially there's no intellisense anymore. What do you think?

adam commented

2025-12-29 08:29:50 +01:00

@StefH commented on GitHub (Sep 3, 2023):

@sprudel79
Thanks for the research.

I was wondering, will this fix also work the other way around, so if I define that Alias in the code from WireMock?

@StefH commented on GitHub (Sep 3, 2023): @sprudel79 Thanks for the research. I was wondering, will this fix also work the other way around, so if I define that Alias in the code from WireMock?

adam commented

2025-12-29 08:29:50 +01:00

@sprudel79 commented on GitHub (Sep 4, 2023):

Thanks to you for taking this up.
I am not sure if this helps, is there any API in WireMock.Net that exposes any type of MimeKit (which I doubt)?
We can definitely give this a try if you like, I can test this approach from my side.

@sprudel79 commented on GitHub (Sep 4, 2023): Thanks to you for taking this up. I am not sure if this helps, is there any API in WireMock.Net that exposes any type of MimeKit (which I doubt)? We can definitely give this a try if you like, I can test this approach from my side.

adam commented

2025-12-29 08:29:50 +01:00

@StefH commented on GitHub (Sep 4, 2023):

is there any API in WireMock.Net that exposes any type of MimeKit (which I doubt)?

No, as far as I can see, I don't expose MimeKit in an api.

@StefH commented on GitHub (Sep 4, 2023): > is there any API in WireMock.Net that exposes any type of MimeKit (which I doubt)? No, as far as I can see, I don't expose MimeKit in an api.

adam commented

2025-12-29 08:29:50 +01:00

@StefH commented on GitHub (Sep 4, 2023):

https://github.com/WireMock-Net/WireMock.Net/pull/999

@StefH commented on GitHub (Sep 4, 2023): https://github.com/WireMock-Net/WireMock.Net/pull/999

adam commented

2025-12-29 08:29:50 +01:00

@StefH commented on GitHub (Sep 4, 2023):

@sprudel79
Can you try preview 1.5.35-ci-17784 ?

https://github.com/WireMock-Net/WireMock.Net/wiki/MyGet-preview-versions

@StefH commented on GitHub (Sep 4, 2023): @sprudel79 Can you try preview 1.5.35-ci-17784 ? https://github.com/WireMock-Net/WireMock.Net/wiki/MyGet-preview-versions

adam commented

2025-12-29 08:29:51 +01:00

@sprudel79 commented on GitHub (Sep 5, 2023):

Thank you very much @StefH, I have updated my environment to use the preview version of WireMock.Net. Furthermore I have removed my local alias handling.
Unfortunately I get again the error from my first post about "The type 'MimeMessage' exists in both...".

@sprudel79 commented on GitHub (Sep 5, 2023): Thank you very much @StefH, I have updated my environment to use the preview version of WireMock.Net. Furthermore I have removed my local alias handling. Unfortunately I get again the error from my first post about "The type 'MimeMessage' exists in both...".

adam commented

2025-12-29 08:29:51 +01:00

@StefH commented on GitHub (Sep 6, 2023):

@sprudel79
In that case there is no solution (yet) in WireMock, so I'll create a wiki page from this issue and close it.

@StefH commented on GitHub (Sep 6, 2023): @sprudel79 In that case there is no solution (yet) in WireMock, so I'll create a wiki page from this issue and close it.

adam commented

2025-12-29 08:29:51 +01:00