btcpayserver/BTCPayServer/Services/Mails/EmailSender.cs

using System;
using System.Net.Mail;
using System.Threading.Tasks;
using BTCPayServer.Logging;
using Microsoft.Extensions.Logging;
using MimeKit;
using NBitcoin;

namespace BTCPayServer.Services.Mails
{
    public abstract class EmailSender : IEmailSender
    {
        public Logs Logs { get; }

        readonly IBackgroundJobClient _JobClient;

        public EmailSender(IBackgroundJobClient jobClient, Logs logs)
        {
            Logs = logs;
            _JobClient = jobClient ?? throw new ArgumentNullException(nameof(jobClient));
        }

        public void SendEmail(string email, string subject, string message)
        {
            _JobClient.Schedule(async (cancellationToken) =>
            {
                var emailSettings = await GetEmailSettings();
                if (emailSettings?.IsComplete() != true)
                {
                    Logs.Configuration.LogWarning("Should have sent email, but email settings are not configured");
                    return;
                }
                using (var smtp = await emailSettings.CreateSmtpClient())
                {
                    var mail = emailSettings.CreateMailMessage(new MailboxAddress(email, email), subject, message, true);
                    await smtp.SendAsync(mail, cancellationToken);
                    await smtp.DisconnectAsync(true, cancellationToken);
                }
            }, TimeSpan.Zero);
        }

        public abstract Task<EmailSettings> GetEmailSettings();
    }
}