System.Net.Mail.Tests.SmtpClientTest.SendMail_DeliveryFormat_SubjectEncoded functional test failed on OSX (release mono) #41506

  Starting:    System.Net.Mail.Functional.Tests (parallel test collections = on, max threads = 4)
   System.Net.Mail.Functional.Tests: [Long Running Test] 'System.Net.Mail.Tests.SmtpClientTest.SendMail_DeliveryFormat_SubjectEncoded', Elapsed: 00:02:00
    System.Net.Mail.Tests.SmtpClientTest.SendMail_DeliveryFormat_SubjectEncoded(useAsyncSend: True, useSevenBit: False, useSmtpUTF8: False) [FAIL]
      System.AggregateException : One or more errors occurred. (Syntax error, command unrecognized. The server response was: )
      ---- System.Net.Mail.SmtpException : Syntax error, command unrecognized. The server response was: 
      Stack Trace:
        /_/src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/Task.cs(1866,0): at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
        /_/src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/Task.cs(2716,0): at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
        /_/src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/Task.cs(2585,0): at System.Threading.Tasks.Task.Wait()
        /_/src/libraries/System.Net.Mail/tests/Functional/SmtpClientTest.cs(422,0): at System.Net.Mail.Tests.SmtpClientTest.SendMail_DeliveryFormat_SubjectEncoded(Boolean useAsyncSend, Boolean useSevenBit, Boolean useSmtpUTF8)
        /_/src/mono/netcore/System.Private.CoreLib/src/System/Reflection/RuntimeMethodInfo.cs(384,0): at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
        ----- Inner Stack Trace -----
        /_/src/libraries/System.Net.Mail/src/System/Net/Mail/SmtpConnection.cs(413,0): at System.Net.Mail.SmtpConnection.ConnectAndHandshakeAsyncResult.End(IAsyncResult result)
        /_/src/libraries/System.Net.Mail/src/System/Net/Mail/SmtpConnection.cs(364,0): at System.Net.Mail.SmtpConnection.EndGetConnection(IAsyncResult result)
        /_/src/libraries/System.Net.Mail/src/System/Net/Mail/SmtpTransport.cs(150,0): at System.Net.Mail.SmtpTransport.EndGetConnection(IAsyncResult result)
        /_/src/libraries/System.Net.Mail/src/System/Net/Mail/SmtpClient.cs(971,0): at System.Net.Mail.SmtpClient.ConnectCallback(IAsyncResult result)
   System.Net.Mail.Functional.Tests: [Long Running Test] 'System.Net.Mail.Tests.SmtpClientTest.SendMailAsync_CanBeCanceled_CancellationToken', Elapsed: 00:02:00
    System.Net.Mail.Tests.SmtpClientTest.SendMailAsync_CanBeCanceled_CancellationToken [FAIL]
      System.Net.Mail.SmtpException : Syntax error, command unrecognized. The server response was: 
      Stack Trace:
        /_/src/libraries/System.Net.Mail/src/System/Net/Mail/SmtpConnection.cs(413,0): at System.Net.Mail.SmtpConnection.ConnectAndHandshakeAsyncResult.End(IAsyncResult result)
        /_/src/libraries/System.Net.Mail/src/System/Net/Mail/SmtpConnection.cs(364,0): at System.Net.Mail.SmtpConnection.EndGetConnection(IAsyncResult result)
        /_/src/libraries/System.Net.Mail/src/System/Net/Mail/SmtpTransport.cs(150,0): at System.Net.Mail.SmtpTransport.EndGetConnection(IAsyncResult result)
        /_/src/libraries/System.Net.Mail/src/System/Net/Mail/SmtpClient.cs(971,0): at System.Net.Mail.SmtpClient.ConnectCallback(IAsyncResult result)
        --- End of stack trace from previous location ---
        /_/src/libraries/System.Net.Mail/tests/Functional/SmtpClientTest.cs(481,0): at System.Net.Mail.Tests.SmtpClientTest.SendMailAsync_CanBeCanceled_CancellationToken()
        --- End of stack trace from previous location ---
  Finished:    System.Net.Mail.Functional.Tests