判断Email地址是否有效

     判断Email地址是否有效
  作者:王俊
  　　在用ASP编写页面时，如果涉及到邮件发送，一般会要求输入Email地址。错误的Email地址往往带来许多不必要的麻烦，用下面的函数IsValidEmail就能判断出一个Email地址是否有效。
  函数源代码：
  <%
  Function IsValidEmail(Email)
  ValidFlag = False
  If (Email <> "") And (InStr(1, Email, "@") > 0) And (InStr(1, Email, ".") > 0) Then
  atCount = 0
  SpecialFlag = False
  For atLoop = 1 To Len(Email)
  atChr = Mid(Email, atLoop, 1)
  If atChr = "@" Then atCount = atCount + 1
  If (atChr >= Chr(32)) And (atChr <= Chr(44)) Then SpecialFlag = True
  If (atChr = Chr(47)) Or (atChr = Chr(96)) Or (atChr >= Chr(123)) Then SpecialFlag = True
  If (atChr >= Chr(58)) And (atChr <= Chr(63)) Then SpecialFlag = True
  If (atChr >= Chr(91)) And (atChr <= Chr(94)) Then SpecialFlag = True
  Next
  If (atCount = 1) And (SpecialFlag = False) Then
  BadFlag = False
  tAry1 = Split(Email, "@")
  UserName = tAry1(0)
  DomainName = tAry1(1)
  If (UserName = "") Or (DomainName = "") Then BadFlag = True
  If Mid(DomainName, 1, 1) = "." then BadFlag = True
  If Mid(DomainName, Len(DomainName), 1) = "." then BadFlag = True
  ValidFlag = True
  End If
  End If
  If BadFlag = True Then ValidFlag = False
  IsValidEmail = ValidFlag
  End Function
  %>
  用法举例：
  IsValidEmail("my_263_email@263.net") 返回Ture
  IsValidEmail("zh99wj@tonghua.com.cn") 返回Ture
  IsValidEmail("myemail263.net") 返回False
  IsValidEmail("my_263_email@263) 返回False
  请注意，函数只是判断Email地址格式是否有效，但并不能检查该地址是否确实存在。