判断 邮箱格式是否正确

 1  Console.Write("请输入邮箱地址：");
 2             string m = Console.ReadLine();
 3             if (m.IndexOf("@") == m.LastIndexOf("@"))
 4             {
 5                 if (m.IndexOf("@") != 0)
 6                 {
 7                     string a = m.Substring(m.IndexOf("@"));
 8                     bool b=a.Contains(".");
 9                     if (b == true)
10                     {
11                         if (a.IndexOf(".") != 1)
12                         {
13                             if (m.Length - 1 != m.LastIndexOf("."))
14                             {
15                                 Console.WriteLine("您输入的格式正确！");
16                             }
17                             else
18                             {
19                                 Console.WriteLine("您输入的格式有误！");
20                             }
21                         }
22                         else
23                         {
24                             Console.WriteLine("您输入的格式有误！");
25                         }
26                     }
27                     else
28                     {
29                         Console.WriteLine("您输入的格式有误！");
30                     }
31                 }
32                 else
33                 {
34 
35                     Console.WriteLine("您输入的格式有误！");
36                 }
37             }
38             else
39             {
40                 Console.WriteLine("您输入的格式有误！");
41             }
42 
43             Console.ReadLine();