Startup.cs

public void ConfigureServices(IServiceCollection services)
{
    // ...

    services.AddTransient<IJobFactory, AspJobFactory>(
        (provider) =>
        {
            return new AspJobFactory( provider );
        } );

    // Quartz jobs anhängen
    services.AddTransient<MailImportJob>(); 
    services.AddTransient<MailSendJob>();
    services.AddTransient<MailReceiveJob>();
    
    // ...
}

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
    // ...
    app.UseQuartz( (quartz) =>
    {
        if (Configuration.GetValue<bool>( "Import:Active", false ))
            quartz.AddJob<MailImportJob>( "MailImport", "Import", Configuration.GetSection( "Import" ).GetValue<int>( "Interval" ) );
        if (Configuration.GetValue<bool>( "Send:Active", false ))
            quartz.AddJob<MailSendJob>( "MailSend", "Send", Configuration.GetSection( "Send" ).GetValue<int>( "Interval" ) );
        if (Configuration.GetValue<bool>( "Receive:Active", false ))
            quartz.AddJob<MailReceiveJob>( "MailReceive", "Receive", Configuration.GetSection( "Receive" ).GetValue<int>( "Interval" ) );
    } );
    
    // ...
}