Initial commit: WpywMail 自建邮件系统：.NET 8 原生 SMTP/IMAP 服务端（DKIM 签名、SPF/DKIM/DMARC 入站校验、SQLite 存储、完整账号体系）、Node 服务端、WinUI 3 客户端与 Web 前端

server-native/DeliveryQueue.cs

@@ -0,0 +1,75 @@
+using System.Net;
+using System.Net.Mail;
+
+namespace WpywMail.Native;
+
+public sealed class DeliveryQueue
+{
+    private readonly AppConfig config;
+    private readonly FileStore store;
+    private readonly DirectSmtpDelivery direct;
+
+    public DeliveryQueue(AppConfig config, FileStore store)
+    {
+        this.config = config;
+        this.store = store;
+        direct = new DirectSmtpDelivery(config, store);
+    }
+
+    public async Task RunAsync(CancellationToken token)
+    {
+        AppLog.Info($"[发送] 投递模式：{(config.DeliveryMode.Equals("relay", StringComparison.OrdinalIgnoreCase) ? "SMTP 中继" : "按 MX 直接投递")}");
+        while (!token.IsCancellationRequested)
+        {
+            foreach (var job in store.TakeDueQueue(10))
+            {
+                try
+                {
+                    var message = store.GetById(job.MessageId) ?? throw new InvalidOperationException("发送队列中的邮件不存在。");
+                    await Deliver(message, job.Recipients, token);
+                    store.CompleteQueue(job);
+                    AppLog.Info($"[发送] 投递成功：{string.Join(", ", job.Recipients)}");
+                }
+                catch (Exception ex)
+                {
+                    store.FailQueue(job, ex);
+                    AppLog.Error($"[发送队列] {job.MessageId} → {string.Join(", ", job.Recipients)}：{ex.Message}");
+                }
+            }
+            await Task.Delay(TimeSpan.FromSeconds(5), token).ContinueWith(_ => { });
+        }
+    }
+
+    private async Task Deliver(MailMessage message, string[] recipients, CancellationToken token)
+    {
+        if (config.DeliveryMode.Equals("relay", StringComparison.OrdinalIgnoreCase))
+        {
+            await DeliverThroughRelay(message, recipients, token);
+            return;
+        }
+
+        await direct.DeliverAsync(message, recipients, token);
+    }
+
+    private async Task DeliverThroughRelay(MailMessage message, string[] recipients, CancellationToken token)
+    {
+        if (string.IsNullOrWhiteSpace(config.Relay.Host)) throw new InvalidOperationException("DeliveryMode=relay 时必须配置 Relay.Host。");
+        using var client = new SmtpClient(config.Relay.Host, config.Relay.Port)
+        {
+            EnableSsl = config.Relay.EnableSsl,
+            DeliveryMethod = SmtpDeliveryMethod.Network,
+            Timeout = 60_000
+        };
+        if (!string.IsNullOrWhiteSpace(config.Relay.User)) client.Credentials = new NetworkCredential(config.Relay.User, config.Relay.Password);
+        using var mail = new System.Net.Mail.MailMessage
+        {
+            From = new MailAddress(message.From),
+            Subject = message.Subject,
+            Body = message.Text,
+            BodyEncoding = System.Text.Encoding.UTF8,
+            SubjectEncoding = System.Text.Encoding.UTF8
+        };
+        foreach (var recipient in recipients) mail.To.Add(recipient);
+        await client.SendMailAsync(mail, token);
+    }
+}