Extension method to have SmtpClient's SendMailAsync respond to a CancellationToken

SmtpClientExtensions.cs

using System;
using System.Net.Mail;
using System.Threading;
using System.Threading.Tasks;

public static class SmtpClientExtensions
{
    /// <summary>
    /// Extension method to have SmtpClient's SendMailAsync respond to a CancellationToken
    /// </summary>
    public static async Task SendMailAsync(
        this SmtpClient client, 
        MailMessage message, 
        CancellationToken token)
    {
        Action cancelSend = () =>
        {
            client.SendAsyncCancel();
        };
        using (var reg = token.Register(cancelSend))
        {
            await client.SendMailAsync(message);
        }
    }
}