New: Require Encryption option for email

Fixes #1908

(cherry picked from commit e704ee617f379ff61fb1bf9fb4044d6b4eb12814)

src/NzbDrone.Core/Notifications/Email/EmailService.cs

@@ -2,6 +2,7 @@ using System;
 using System.Linq;
 using FluentValidation.Results;
 using MailKit.Net.Smtp;
+using MailKit.Security;
 using MimeKit;
 using NLog;
 
@@ -51,7 +52,21 @@ namespace NzbDrone.Core.Notifications.Email
         {
             using (var client = new SmtpClient())
             {
-                client.Connect(settings.Server, settings.Port);
+                var serverOption = SecureSocketOptions.Auto;
+
+                if (settings.RequireEncryption)
+                {
+                    if (settings.Port == 465)
+                    {
+                        serverOption = SecureSocketOptions.SslOnConnect;
+                    }
+                    else
+                    {
+                        serverOption = SecureSocketOptions.StartTls;
+                    }
+                }
+
+                client.Connect(settings.Server, settings.Port, serverOption);
 
                 if (!string.IsNullOrWhiteSpace(settings.Username))
                 {

src/NzbDrone.Core/Notifications/Email/EmailSettings.cs

@@ -22,7 +22,7 @@ namespace NzbDrone.Core.Notifications.Email
 
         public EmailSettings()
         {
-            Port = 25;
+            Port = 587;
         }
 
         [FieldDefinition(0, Label = "Server", HelpText = "Hostname or IP of Email server")]
@@ -31,6 +31,9 @@ namespace NzbDrone.Core.Notifications.Email
         [FieldDefinition(1, Label = "Port")]
         public int Port { get; set; }
 
+        [FieldDefinition(2, Label = "Require Encryption", HelpText = "Require SSL (Port 465 only) or StartTLS (any other port)", Type = FieldType.Checkbox)]
+        public bool RequireEncryption { get; set; }
+
         [FieldDefinition(3, Label = "Username", Privacy = PrivacyLevel.UserName)]
         public string Username { get; set; }