Serilog WriteTo.Email() failing

This is a .Net Core 6 console application that uses Serilog.Sinks.Email 2.4.0. In the same project I am referencing the MailKit 3.1.0 Nuget package. I notice that Serilog.Sinks.Email also references Mailkit 3.1.0.

I'm configuring the Logger like so. My goal is to have Serilog send an email when Log.Fatal() is invoked:

.WriteTo.Email(  
    new EmailConnectionInfo()
    {
        FromEmail = _appSettings.EmailFrom,
        ToEmail = _appSettings.EmailToOnError,
        MailServer = _appSettings.EmailHost,
        EmailSubject = $"Runtime error starting {_appSettings.ApplicationName}",
        ServerCertificateValidationCallback = (s, c, h, e) => true
    },
    restrictedToMinimumLevel: LogEventLevel.Fatal);

I am logging Serilog messages to the Debug output window, like so, so I can see the errors messages that Serilog would otherwise (by design) swallow:

Serilog.Debugging.SelfLog.Enable(msg => Debug.WriteLine(msg));

When I call Log.Fatal(), followed immediately by Log.CloseAndFlush(), and look in the Debug output window, I can see that Serilog tries to send me an email message, but fails, saying that it cannot find the method MailKit.MailTransport.SendAsync(). Any idea what I am missing? Here is the full error message from the Debug output window:

Exception while emitting periodic batch from 
Serilog.Sinks.PeriodicBatching.PeriodicBatchingSink: System.MissingMethodException: 
Method not found: 'System.Threading.Tasks.Task 
MailKit.MailTransport.SendAsync(MimeKit.MimeMessage, System.Threading.CancellationToken, 
MailKit.ITransferProgress)'.
   at Serilog.Sinks.Email.EmailSink.EmitBatchAsync(IEnumerable`1 events)
   at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine] 
   (TStateMachine& stateMachine)
   at Serilog.Sinks.Email.EmailSink.EmitBatchAsync(IEnumerable`1 events)
   at Serilog.Sinks.PeriodicBatching.PeriodicBatchingSink.OnTick()