bitwarden/src/Core/Services/Implementations/MailKitSmtpMailDeliveryService.cs

using System;
using System.Threading.Tasks;
using Bit.Core.Utilities;
using Bit.Core.Settings;
using MailKit.Net.Smtp;
using Microsoft.Extensions.Logging;
using MimeKit;

namespace Bit.Core.Services
{
    public class MailKitSmtpMailDeliveryService : IMailDeliveryService
    {
        private readonly GlobalSettings _globalSettings;
        private readonly ILogger<MailKitSmtpMailDeliveryService> _logger;
        private readonly string _replyDomain;

        public MailKitSmtpMailDeliveryService(
            GlobalSettings globalSettings,
            ILogger<MailKitSmtpMailDeliveryService> logger)
        {
            if (globalSettings.Mail?.Smtp?.Host == null)
            {
                throw new ArgumentNullException(nameof(globalSettings.Mail.Smtp.Host));
            }
            if (globalSettings.Mail?.ReplyToEmail?.Contains("@") ?? false)
            {
                _replyDomain = globalSettings.Mail.ReplyToEmail.Split('@')[1];
            }

            _globalSettings = globalSettings;
            _logger = logger;
        }

        public async Task SendEmailAsync(Models.Mail.MailMessage message)
        {
            var mimeMessage = new MimeMessage();
            mimeMessage.From.Add(new MailboxAddress(_globalSettings.SiteName, _globalSettings.Mail.ReplyToEmail));
            mimeMessage.Subject = message.Subject;
            if (!string.IsNullOrWhiteSpace(_replyDomain))
            {
                mimeMessage.MessageId = $"<{Guid.NewGuid()}@{_replyDomain}>";
            }

            foreach (var address in message.ToEmails)
            {
                mimeMessage.To.Add(MailboxAddress.Parse(address));
            }

            if (message.BccEmails != null)
            {
                foreach (var address in message.BccEmails)
                {
                    mimeMessage.Bcc.Add(MailboxAddress.Parse(address));
                }
            }

            var builder = new BodyBuilder();
            if (!string.IsNullOrWhiteSpace(message.TextContent))
            {
                builder.TextBody = message.TextContent;
            }
            builder.HtmlBody = message.HtmlContent;
            mimeMessage.Body = builder.ToMessageBody();

            using (var client = new SmtpClient())
            {
                if (_globalSettings.Mail.Smtp.TrustServer)
                {
                    client.ServerCertificateValidationCallback = (s, c, h, e) => true;
                }

                if (!_globalSettings.Mail.Smtp.StartTls && !_globalSettings.Mail.Smtp.Ssl &&
                    _globalSettings.Mail.Smtp.Port == 25)
                {
                    await client.ConnectAsync(_globalSettings.Mail.Smtp.Host, _globalSettings.Mail.Smtp.Port,
                        MailKit.Security.SecureSocketOptions.None);
                }
                else
                {
                    var useSsl = _globalSettings.Mail.Smtp.Port == 587 && !_globalSettings.Mail.Smtp.SslOverride ?
                        false : _globalSettings.Mail.Smtp.Ssl;
                    await client.ConnectAsync(_globalSettings.Mail.Smtp.Host, _globalSettings.Mail.Smtp.Port, useSsl);
                }

                if (CoreHelpers.SettingHasValue(_globalSettings.Mail.Smtp.Username) &&
                    CoreHelpers.SettingHasValue(_globalSettings.Mail.Smtp.Password))
                {
                    await client.AuthenticateAsync(_globalSettings.Mail.Smtp.Username,
                        _globalSettings.Mail.Smtp.Password);
                }

                await client.SendAsync(mimeMessage);
                await client.DisconnectAsync(true);
            }
        }
    }
}