Send mail via System.Net.Mail.SmtpClient isn't working on Android, but on Windows

[tsjdev-apps]

Description

I've created a small sample trying to send an email using theSystem.Net.Mail.SmtpClient. The sample is working on Windows, but not on Android. An Interop+AndroidCrypto+SslException is thrown.

Steps to Reproduce

1. Create a File > New .NET MAUI App
2. Create a System.Net.Mail.SmtpClient and calling the SendMailAsync() on Android
3. An Interop+AndroidCrypto+SslException is thrown
4. Run the same code on Windows and the email is sent

I've tried using an outlook.com mail address with the smtp-mail.outlook.com host.

See the following basic sample:
MauiSendMailSample.zip

Version with bug

6.0.486 (current)

Last version that worked well

Unknown/Other

Affected platforms

Android, I was not able test on other platforms

Affected platform versions

Android

Did you find any workaround?

No response

Relevant log output

{System.Net.Mail.SmtpException: Failure sending mail.
 ---> System.Security.Authentication.AuthenticationException: Authentication failed, see inner exception.
 ---> Interop+AndroidCrypto+SslException: Exception of type 'Interop+AndroidCrypto+SslException' was thrown.
   --- End of inner exception stack trace ---
   at System.Net.Security.SslStream.<ForceAuthenticationAsync>d__175`1[[System.Net.Security.AsyncReadWriteAdapter, System.Net.Security, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a]].MoveNext()
   at System.Threading.Tasks.TaskToApm.End(IAsyncResult asyncResult)
   at System.Net.Security.SslStream.EndAuthenticateAsClient(IAsyncResult asyncResult)
   at System.Net.TlsStream.EndAuthenticateAsClient(IAsyncResult asyncResult)
   at System.Net.Mail.SmtpConnection.ConnectAndHandshakeAsyncResult.TlsStreamAuthenticateCallback(IAsyncResult result)
--- End of stack trace from previous location ---
   at System.Net.Mail.SmtpConnection.ConnectAndHandshakeAsyncResult.End(IAsyncResult result)
   at System.Net.Mail.SmtpConnection.EndGetConnection(IAsyncResult result)
   at System.Net.Mail.SmtpTransport.EndGetConnection(IAsyncResult result)
   at System.Net.Mail.SmtpClient.ConnectCallback(IAsyncResult result)
   --- End of inner exception stack trace ---
   at MauiSendMailSample.MainPage.OnMailButtonClicked(Object sender, EventArgs e) in MauiSendMailSample\MauiSendMailSample\MainPage.xaml.cs:line 36}

[janseris]

Seems there are SSL issues with Android in. NET in multiple technologies.
Adding to my list, it is currently:
gRPC, WebSocket, SQL Server and SMTP

dotnet/android#7277

[jfversluis]

As pointed out this seems to be at least a layer deeper on the Android bindings or maybe even on the plugin/.NET runtime in this case. Unfortunately this is not something that we can do something about in the .NET MAUI project.

[janseris]

@jfversluis can you give a tip how to solve that? Where to report etc.? Thank you

[tsjdev-apps]

I just tested the same sample on Xamarin.Forms and on Android/UWP it is working like expected.
Only .NET MAUI Android isn't working as expected.

[MohammdaSalah]

So any workaround to this?

[knocte]

I just tested the same sample on Xamarin.Forms and on Android/UWP it is working like expected.
Only .NET MAUI Android isn't working as expected.

If this is true then this issue needs to be reopened @jfversluis

[tsjdev-apps]

I just tested the same sample on Xamarin.Forms and on Android/UWP it is working like expected.
Only .NET MAUI Android isn't working as expected.

If this is true then this issue needs to be reopened @jfversluis

For me this exception only got raised if I'm running the sample on an emulator for .NET MAUI. If I'm running the code on a real device (I've tested with Android 11 and Android 12) it is also running.

The Xamarin version is running on an emulator and on a real device.

[dmsch]

This issue also occurs with SignalR on Android 8.0.
With Android 9.0 and above, SignalR works.

[janseris]

This issue also occurs with SignalR on Android 8.0. With Android 9.0 and above, SignalR works.

Could you create a new issue? I think @jfversluis doesn't plan to reopen this one
I'll be happy to track it because this seems like a much broader problem with Android SSL providers