初步完成邮件功能

DMS.Core/Models/EmailLog.cs

@@ -0,0 +1,43 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace DMS.Core.Models
+{
+    /// <summary>
+    /// 邮件日志实体
+    /// </summary>
+    public class EmailLog
+    {
+        /// <summary>
+        /// 日志ID
+        /// </summary>
+        public int Id { get; set; }
+
+        /// <summary>
+        /// 关联的邮件ID
+        /// </summary>
+        public int EmailMessageId { get; set; }
+
+        /// <summary>
+        /// 日志级别
+        /// </summary>
+        [Required]
+        [MaxLength(20)]
+        public string Level { get; set; }
+
+        /// <summary>
+        /// 日志消息
+        /// </summary>
+        [Required]
+        public string Message { get; set; }
+
+        /// <summary>
+        /// 异常详情
+        /// </summary>
+        public string? Exception { get; set; }
+
+        /// <summary>
+        /// 创建时间
+        /// </summary>
+        public DateTime CreatedAt { get; set; } = DateTime.Now;
+    }
+}