deprecate smtpclient for mailkit smtp service

src/Core/Core.csproj

@@ -14,6 +14,7 @@
   <ItemGroup>
     <PackageReference Include="Handlebars.Net" Version="1.9.5" />
     <PackageReference Include="IdentityServer4.AccessTokenValidation" Version="2.6.0" />
+    <PackageReference Include="MailKit" Version="2.1.2" />
     <PackageReference Include="Microsoft.AspNetCore.DataProtection.AzureStorage" Version="2.1.1" />
     <PackageReference Include="Microsoft.AspNetCore.HttpOverrides" Version="2.1.1" />
     <PackageReference Include="Microsoft.AspNetCore.Identity" Version="2.1.3" />

src/Core/GlobalSettings.cs

@@ -117,6 +117,7 @@ namespace Bit.Core
                 public string Password { get; set; }
                 public bool UseDefaultCredentials { get; set; } = false;
                 public string AuthType { get; set; }
+                public bool TrustServer { get; set; } = false;
             }
         }
 

src/Core/Services/Implementations/MailKitSmtpMailDeliveryService.cs

@@ -0,0 +1,84 @@
+using System;
+using System.Threading.Tasks;
+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(new MailboxAddress(address));
+            }
+
+            if(message.BccEmails != null)
+            {
+                foreach(var address in message.BccEmails)
+                {
+                    mimeMessage.Bcc.Add(new MailboxAddress(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;
+                }
+
+                var useSsl = _globalSettings.Mail.Smtp.Port == 587 ? false : _globalSettings.Mail.Smtp.Ssl;
+                await client.ConnectAsync(_globalSettings.Mail.Smtp.Host, _globalSettings.Mail.Smtp.Port, useSsl);
+
+                if(!_globalSettings.Mail.Smtp.UseDefaultCredentials)
+                {
+                    await client.AuthenticateAsync(_globalSettings.Mail.Smtp.Username,
+                        _globalSettings.Mail.Smtp.Password);
+                }
+
+                await client.SendAsync(mimeMessage);
+                await client.DisconnectAsync(true);
+            }
+        }
+    }
+}

src/Core/Services/Implementations/SmtpMailDeliveryService.cs

@@ -7,6 +7,7 @@ using Microsoft.Extensions.Logging;
 
 namespace Bit.Core.Services
 {
+    [Obsolete]
     public class SmtpMailDeliveryService : IMailDeliveryService
     {
         private readonly GlobalSettings _globalSettings;

src/Core/Utilities/ServiceCollectionExtensions.cs

@@ -87,7 +87,7 @@ namespace Bit.Core.Utilities
             }
             else if(CoreHelpers.SettingHasValue(globalSettings.Mail?.Smtp?.Host))
             {
-                services.AddSingleton<IMailDeliveryService, SmtpMailDeliveryService>();
+                services.AddSingleton<IMailDeliveryService, MailKitSmtpMailDeliveryService>();
             }
             else
             {