case 4670 whups nearly missed an addition of services all ready to merge now for real

Services/MailSender.cs

@@ -0,0 +1,47 @@
+using System.Threading.Tasks;
+using MailKit.Net.Smtp;
+using MailKit.Security;
+using Microsoft.Extensions.Configuration;
+using MimeKit;
+
+namespace contact.Services
+{
+    //Sends web form submissions to support.
+    //From is always the authenticated account; the visitor goes in Reply-To, so there is no sender spoofing.
+    //SMTP settings come from the "Smtp" config section; the password is never in source.
+    public class MailSender
+    {
+        private const string SupportAddress = "support@ayanova.com";
+        private readonly IConfiguration _configuration;
+
+        public MailSender(IConfiguration configuration)
+        {
+            _configuration = configuration;
+        }
+
+        public async Task SendToSupportAsync(string subject, string body, string visitorName, string visitorEmail)
+        {
+            var smtp = _configuration.GetSection("Smtp");
+
+            var message = new MimeMessage();
+            message.From.Add(new MailboxAddress("AyaNova web forms", smtp["User"]));
+            message.To.Add(MailboxAddress.Parse(SupportAddress));
+            if (MailboxAddress.TryParse(visitorEmail, out var replyTo))
+            {
+                replyTo.Name = visitorName;
+                message.ReplyTo.Add(replyTo);
+            }
+            message.Subject = OneLine(subject);
+            message.Body = new TextPart("plain") { Text = body };
+
+            using var client = new SmtpClient();
+            await client.ConnectAsync(smtp["Host"], smtp.GetValue<int>("Port"), SecureSocketOptions.StartTls);
+            await client.AuthenticateAsync(smtp["User"], smtp["Password"]);
+            await client.SendAsync(message);
+            await client.DisconnectAsync(true);
+        }
+
+        //Subjects include visitor-supplied text; a hand-crafted POST could put line breaks in it
+        private static string OneLine(string s) => s.Replace("\r", " ").Replace("\n", " ");
+    }
+}