如何使用.NET Framework验证电子邮件地址格式？

时间：2009-08-25 21:22:52

标签： .net vb.net validation email

我想要一个函数来测试字符串的格式是否像电子邮件地址一样。

.NET框架内置了什么来实现这一目标？

这有效：

Function IsValidEmailFormat(ByVal s As String) As Boolean
    Try
        Dim a As New System.Net.Mail.MailAddress(s)
    Catch
        Return False
    End Try
    Return True
End Function

但是，有更优雅的方式吗？

11 个答案:

答案 0 :(得分：57)

不要打扰自己的验证。 .NET 4.0通过MailAddress类显着改进了验证。只需使用MailAddress address = new MailAddress(input)，如果它抛出，则无效。如果您的输入有任何可能的解释作为符合RFC 2822的电子邮件地址规范，它将解析它。上面的正则表达式，甚至是MSDN第一篇文章都是错误的，因为它们没有考虑显示名称，引用的本地部分，域的域文字值，本地部分的正确点原子规范，可能性邮件地址可以在尖括号中，显示名称的多个引用字符串值，转义字符，显示名称中的unicode，注释和最大有效邮件地址长度。我花了三周的时间在.NET 4.0中为System.Net.Mail重写邮件地址解析器并相信我，因为有很多边缘情况，所以比提出一些正则表达式更难。 .NET 4.0 beta 2中的MailAddress类将具有这种改进的功能。

还有一件事，您唯一可以验证的是邮件地址的格式。您无法验证电子邮件地址是否真正适用于接收电子邮件而不向该地址发送电子邮件，并查看服务器是否接受该电子邮件以进行传递。这是不可能的，虽然有SMTP命令可以给邮件服务器尝试验证它，但很多时候这些命令将被禁用或返回不正确的结果，因为这是垃圾邮件发送者查找电子邮件地址的常用方法。

答案 1 :(得分：7)

MSDN文章：How to: Verify That Strings are in Valid E-Mail Format

此示例方法调用Regex.IsMatch（String，String）方法以验证字符串是否符合正则表达式模式。

Function IsValidEmailFormat(ByVal s As String) As Boolean
    Return Regex.IsMatch(s, "^([0-9a-zA-Z]([-\.\w]*[0-9a-zA-Z])*@([0-9a-zA-Z][-\w]*[0-9a-zA-Z]\.)+[a-zA-Z]{2,9})$")
End Function

答案 2 :(得分：3)

'-----------------------------------------------------------------------

'Creater : Rachitha Madusanka

'http://www.megazoon.com

'jewandara@gmail.com

'jewandara@hotmail.com

'Web Designer and Software Developer

'@ http://www.zionx.net16.net

'-----------------------------------------------------------------------




Function ValidEmail(ByVal strCheck As String) As Boolean
    Try
        Dim bCK As Boolean
        Dim strDomainType As String


        Const sInvalidChars As String = "!#$%^&*()=+{}[]|\;:'/?>,< "
        Dim i As Integer

        'Check to see if there is a double quote
        bCK = Not InStr(1, strCheck, Chr(34)) > 0
        If Not bCK Then GoTo ExitFunction

        'Check to see if there are consecutive dots
        bCK = Not InStr(1, strCheck, "..") > 0
        If Not bCK Then GoTo ExitFunction

        ' Check for invalid characters.
        If Len(strCheck) > Len(sInvalidChars) Then
            For i = 1 To Len(sInvalidChars)
                If InStr(strCheck, Mid(sInvalidChars, i, 1)) > 0 Then
                    bCK = False
                    GoTo ExitFunction
                End If
            Next
        Else
            For i = 1 To Len(strCheck)
                If InStr(sInvalidChars, Mid(strCheck, i, 1)) > 0 Then
                    bCK = False
                    GoTo ExitFunction
                End If
            Next
        End If

        If InStr(1, strCheck, "@") > 1 Then 'Check for an @ symbol
            bCK = Len(Left(strCheck, InStr(1, strCheck, "@") - 1)) > 0
        Else
            bCK = False
        End If
        If Not bCK Then GoTo ExitFunction

        strCheck = Right(strCheck, Len(strCheck) - InStr(1, strCheck, "@"))
        bCK = Not InStr(1, strCheck, "@") > 0 'Check to see if there are too many @'s
        If Not bCK Then GoTo ExitFunction

        strDomainType = Right(strCheck, Len(strCheck) - InStr(1, strCheck, "."))
        bCK = Len(strDomainType) > 0 And InStr(1, strCheck, ".") < Len(strCheck)
        If Not bCK Then GoTo ExitFunction

        strCheck = Left(strCheck, Len(strCheck) - Len(strDomainType) - 1)
        Do Until InStr(1, strCheck, ".") <= 1
            If Len(strCheck) >= InStr(1, strCheck, ".") Then
                strCheck = Left(strCheck, Len(strCheck) - (InStr(1, strCheck, ".") - 1))
            Else
                bCK = False
                GoTo ExitFunction
            End If
        Loop
        If strCheck = "." Or Len(strCheck) = 0 Then bCK = False

ExitFunction:
        ValidEmail = bCK
    Catch ex As ArgumentException
        Return False
    End Try
    Return ValidEmail
End Function

答案 3 :(得分：2)

首先您必须通过输入错误的符号来限制用户，您可以使用文本框KeyPress事件来执行此操作

Private Sub txtemailid_KeyPress(ByVal sender As System.Object, 
                                ByVal e As System.Windows.FormsKeyPressEventArgs) Handles txtemailid.KeyPress

    Dim ac As String = "@"
    If e.KeyChar <> ChrW(Keys.Back) Then
        If Asc(e.KeyChar) < 97 Or Asc(e.KeyChar) > 122 Then
            If Asc(e.KeyChar) <> 46 And Asc(e.KeyChar) <> 95 Then
                If Asc(e.KeyChar) < 48 Or Asc(e.KeyChar) > 57 Then
                    If ac.IndexOf(e.KeyChar) = -1 Then
                        e.Handled = True

                    Else

                        If txtemailid.Text.Contains("@") And e.KeyChar = "@" Then
                            e.Handled = True
                        End If

                    End If


                End If
            End If
        End If

    End If

End Sub

以上代码只允许用户输入a-z（小），0到9（数字），@，。，_

使用文本框控件的验证事件后，使用正则表达式验证电子邮件ID 

Private Sub txtemailid_Validating(ByVal sender As System.Object, 
                                  ByVal e As System.ComponentModel.CancelEventArgs) 
    Handles txtemailid.Validating

    Dim pattern As String = "^[a-z][a-z|0-9|]*([_][a-z|0-9]+)*([.][a-z|0-9]+([_][a-z|0-9]+)*)?@[a-z][a-z|0-9|]*\.([a-z][a-z|0-9]*(\.[a-z][a-z|0-9]*)?)$"


    Dim match As System.Text.RegularExpressions.Match = Regex.Match(txtemailid.Text.Trim(), pattern, RegexOptions.IgnoreCase)
    If (match.Success) Then
        MessageBox.Show("Success", "Checking")
    Else
        MessageBox.Show("Please enter a valid email id", "Checking")
        txtemailid.Clear()
    End If
End Sub

答案 4 :(得分：2)

    Public Function ValidateEmail(ByVal strCheck As String) As Boolean
        Try
            Dim vEmailAddress As New System.Net.Mail.MailAddress(strCheck)
        Catch ex As Exception
            Return False
        End Try
        Return True
    End Function

答案 5 :(得分：1)

您应该使用 Regular Expressions来验证电子邮件地址。

答案 6 :(得分：1)

我已经测试了批准的答案＆＃39;在这种情况下，它似乎不符合实际有效电子邮件地址的规范。经过多次头痛，我发现这个正则表达式比微软做得好得多。 

"(?:(?:\r\n)?[ \t])*(?:(?:(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t]" +
")+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|""(?:[^\""\r\\]|\\.|(?:(?:\r\n)?[ \t]))*""(?:(?:" +
"\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(" +
"?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|""(?:[^\""\r\\]|\\.|(?:(?:\r\n)?[ " +
"\t]))*""(?:(?:\r\n)?[ \t])*))*@(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\"".\[\] \000-\0" +
"31]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|\[([^\[\]\r\\]|\\.)*\" +
"](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\"".\[\] \000-\031]+" +
"(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:" +
"(?:\r\n)?[ \t])*))*|(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z" +
"|(?=[\[""()<>@,;:\\"".\[\]]))|""(?:[^\""\r\\]|\\.|(?:(?:\r\n)?[ \t]))*""(?:(?:\r\n)" +
"?[ \t])*)*\<(?:(?:\r\n)?[ \t])*(?:@(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\" +
"r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[" +
" \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)" +
"?[ \t])+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t]" +
")*))*(?:,@(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[" +
" \t])+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*" +
")(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t]" +
")+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*)" +
"*:(?:(?:\r\n)?[ \t])*)?(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+" +
"|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|""(?:[^\""\r\\]|\\.|(?:(?:\r\n)?[ \t]))*""(?:(?:\r" +
"\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:" +
"\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|""(?:[^\""\r\\]|\\.|(?:(?:\r\n)?[ \t" +
"]))*""(?:(?:\r\n)?[ \t])*))*@(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\"".\[\] \000-\031" +
"]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|\[([^\[\]\r\\]|\\.)*\](" +
"?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\"".\[\] \000-\031]+(?" +
":(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?" +
":\r\n)?[ \t])*))*\>(?:(?:\r\n)?[ \t])*)|(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?" +
":(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|""(?:[^\""\r\\]|\\.|(?:(?:\r\n)?" +
"[ \t]))*""(?:(?:\r\n)?[ \t])*)*:(?:(?:\r\n)?[ \t])*(?:(?:(?:[^()<>@,;:\\"".\[\] " +
"\000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|""(?:[^\""\r\\]|" +
"\\.|(?:(?:\r\n)?[ \t]))*""(?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>" +
"@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|""" +
"(?:[^\""\r\\]|\\.|(?:(?:\r\n)?[ \t]))*""(?:(?:\r\n)?[ \t])*))*@(?:(?:\r\n)?[ \t]" +
")*(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\" +
""".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?" +
":[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\"".\[" +
"\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*|(?:[^()<>@,;:\\"".\[\] \000-" +
"\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|""(?:[^\""\r\\]|\\.|(" +
"?:(?:\r\n)?[ \t]))*""(?:(?:\r\n)?[ \t])*)*\<(?:(?:\r\n)?[ \t])*(?:@(?:[^()<>@,;" +
":\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|\[([" +
"^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\""" +
".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|\[([^\[\" +
"]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*(?:,@(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\"".\" +
"[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|\[([^\[\]\" +
"r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\"".\[\] " +
"\000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|\[([^\[\]\r\\]" +
"|\\.)*\](?:(?:\r\n)?[ \t])*))*)*:(?:(?:\r\n)?[ \t])*)?(?:[^()<>@,;:\\"".\[\] \0" +
"00-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|""(?:[^\""\r\\]|\\" +
".|(?:(?:\r\n)?[ \t]))*""(?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@," +
";:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|""(?" +
":[^\""\r\\]|\\.|(?:(?:\r\n)?[ \t]))*""(?:(?:\r\n)?[ \t])*))*@(?:(?:\r\n)?[ \t])*" +
"(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\""." +
"\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[" +
"^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\"".\[\]" +
"]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*\>(?:(?:\r\n)?[ \t])*)(?:,\s*(" +
"?:(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\" +
""".\[\]]))|""(?:[^\""\r\\]|\\.|(?:(?:\r\n)?[ \t]))*""(?:(?:\r\n)?[ \t])*)(?:\.(?:(" +
"?:\r\n)?[ \t])*(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[" +
"\[""()<>@,;:\\"".\[\]]))|""(?:[^\""\r\\]|\\.|(?:(?:\r\n)?[ \t]))*""(?:(?:\r\n)?[ \t" +
"])*))*@(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t" +
"])+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?" +
":\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|" +
"\Z|(?=[\[""()<>@,;:\\"".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*|(?:" +
"[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\"".\[\" +
"]]))|""(?:[^\""\r\\]|\\.|(?:(?:\r\n)?[ \t]))*""(?:(?:\r\n)?[ \t])*)*\<(?:(?:\r\n)" +
"?[ \t])*(?:@(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""" +
"()<>@,;:\\"".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)" +
"?[ \t])*(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>" +
"@,;:\\"".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*(?:,@(?:(?:\r\n)?[" +
" \t])*(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@," +
";:\\"".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t]" +
")*(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\" +
""".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*)*:(?:(?:\r\n)?[ \t])*)?" +
"(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[""()<>@,;:\\""." +
"\[\]]))|""(?:[^\""\r\\]|\\.|(?:(?:\r\n)?[ \t]))*""(?:(?:\r\n)?[ \t])*)(?:\.(?:(?:" +
"\r\n)?[ \t])*(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[" +
"""()<>@,;:\\"".\[\]]))|""(?:[^\""\r\\]|\\.|(?:(?:\r\n)?[ \t]))*""(?:(?:\r\n)?[ \t])" +
"*))*@(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])" +
"+|\Z|(?=[\[""()<>@,;:\\"".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\" +
".(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\"".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z" +
"|(?=[\[""()<>@,;:\\"".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*\>(?:(" +
"?:\r\n)?[ \t])*))*)?;\s*)"

我已经使用简单的应用程序将其格式化为vb字符串。太糟糕的堆栈溢出更像是一个编码存储库＆＃39;而不是对问题的完整答案。

答案 7 :(得分：1)

另一个用于检查电子邮件是否有效的功能：

Public Function ValidEmail(ByVal strCheck As String) As Boolean
    Try
        Dim bCK As Boolean
        Dim strDomainType As String
        Const sInvalidChars As String = "!#$%^&*()=+{}[]|\;:'/?>,< "
        Dim i As Integer
        'Check to see if there is a double quote
        bCK = Not InStr(1, strCheck, Chr(34)) > 0
        If Not bCK Then GoTo ExitFunction
        'Check to see if there are consecutive dots
        bCK = Not InStr(1, strCheck, "..") > 0
        If Not bCK Then GoTo ExitFunction
        ' Check for invalid characters.
        If Len(strCheck) > Len(sInvalidChars) Then
            For i = 1 To Len(sInvalidChars)
                If InStr(strCheck, Mid(sInvalidChars, i, 1)) > 0 Then
                    bCK = False
                    GoTo ExitFunction
                End If
            Next
        Else
            For i = 1 To Len(strCheck)
                If InStr(sInvalidChars, Mid(strCheck, i, 1)) > 0 Then
                    bCK = False
                    GoTo ExitFunction
                End If
            Next
        End If

        If InStr(1, strCheck, "@") > 1 Then 'Check for an @ symbol
            bCK = Len(Left(strCheck, InStr(1, strCheck, "@") - 1)) > 0
        Else
            bCK = False
        End If
        If Not bCK Then GoTo ExitFunction
        strCheck = Right(strCheck, Len(strCheck) - InStr(1, strCheck, "@"))
        bCK = Not InStr(1, strCheck, "@") > 0 'Check to see if there are too many @'s
        If Not bCK Then GoTo ExitFunction
        strDomainType = Right(strCheck, Len(strCheck) - InStr(1, strCheck, "."))
        bCK = Len(strDomainType) > 0 And InStr(1, strCheck, ".") < Len(strCheck)
        If Not bCK Then GoTo ExitFunction
        strCheck = Left(strCheck, Len(strCheck) - Len(strDomainType) - 1)
        Do Until InStr(1, strCheck, ".") <= 1
            If Len(strCheck) >= InStr(1, strCheck, ".") Then
                strCheck = Left(strCheck, Len(strCheck) - (InStr(1, strCheck, ".") - 1))
            Else
                bCK = False
                GoTo ExitFunction
            End If
        Loop
        If strCheck = "." Or Len(strCheck) = 0 Then bCK = False
ExitFunction:
        ValidEmail = bCK
    Catch ex As ArgumentException
        Return False
    End Try
    Return ValidEmail
End Function

如何使用它：

Private Sub TextBox2_KeyDown(sender As Object, e As KeyEventArgs) Handles TextBox2.KeyDown
    If e.KeyCode = Keys.Enter Then
        If TextBox2.Text = "" Then
            MsgBox("Write Down Your email and Press Enter") : TextBox2.Select()
        Else

            If ValidEmail(TextBox2.Text) Then ' to check if the email is valid or not
                   'do whatever
            Else
                MsgBox("Please Write Valid Email")
                TextBox2.Select()
            End If
        End If
    End If
End Sub

答案 8 :(得分：0)

您可以使用正则表达式来执行此操作。

已经写了很多关于它的文章;当我搜索谷歌搜索“正则表达式验证电子邮件地址”时出现了这个问题：Find or Validate an Email Address。

答案 9 :(得分：0)

诸如“address @ localhost”和“user@192.168.1.2”之类的电子邮件实际上是有效地址，您可以通过运行自己的电子邮件服务器来测试这些地址（通常也可以通过修改主机文件来完成）。 但是，要获得完整的解决方案：

''' <summary>
''' METHODS FOR SENDING AND VALIDATING EMAIL
''' </summary>
''' <remarks></remarks>
Public Class email

    ''' <summary>
    ''' check if email format is valid
    ''' </summary>
    ''' <param name="emailAddress">[required] Email address.</param>
    ''' <param name="disallowLocalDomain">[optional] Allow headers like "@localhost"?</param>
    ''' <param name="allowAlerts">[optional] Enable error messages?</param>
    ''' <returns>Returns true if email is valid and false otherwise.</returns>
    ''' <remarks></remarks>
    Public Shared Function isValid(ByVal emailAddress As String,
                                   Optional ByVal disallowLocalDomain As Boolean = True,
                                   Optional ByVal allowAlerts As Boolean = True
                                   ) As Boolean
        Try
            Dim mailParts() As String = emailAddress.Split("@")
            If mailParts.Length <> 2 Then
                If allowAlerts Then
                    MsgBox("Valid email addresses are formatted [sample@domain.tld]. " &
                           "Your address is missing a header [i.e. ""@domain.tld""].",
                           MsgBoxStyle.Exclamation, "No Header Specified")
                End If
                Return False
            End If
            If mailParts(mailParts.GetLowerBound(0)) = "" Then
                If allowAlerts Then
                    MsgBox("Valid email addresses are formatted [sample@domain.tld]. " &
                           "The username portion of the e-mail address you provided (before the @ symbol) is empty.",
                           MsgBoxStyle.Exclamation, "Invalid Email User")
                End If
                Return False
            End If
            Dim headerParts() As String = mailParts(mailParts.GetUpperBound(0)).Split(".")
            If disallowLocalDomain AndAlso headerParts.Length < 2 Then
                If allowAlerts Then
                    MsgBox("Valid email addresses are formatted [sample@domain.tld]. " &
                           "Although addresses formatted like [sample@domain] are valid, " &
                           "only addresses with headers like ""sample.org"", ""sample.com"", and etc. " &
                           "[i.e. @domain.org] are accepted.",
                           MsgBoxStyle.Exclamation, "Invalid Header")
                End If
                Return False
            ElseIf headerParts(headerParts.GetLowerBound(0)) = "" Or
                   headerParts(headerParts.GetUpperBound(0)) = "" Then
                If allowAlerts Then
                    MsgBox("Valid email addresses are formatted [sample@domain.tld]. " &
                           "Your header """ & mailParts(mailParts.GetUpperBound(0)) & """ is invalid.",
                           MsgBoxStyle.Exclamation, "Invalid Header")
                End If
                Return False
            End If
            Dim address As MailAddress = New MailAddress(emailAddress)
        Catch ex As Exception
            If allowAlerts Then
                MsgBox(ex.Message, MsgBoxStyle.Exclamation, "Invalid Email Address")
            End If
            Return False
        End Try
        Return True
    End Function

End Class 'email'

答案 10 :(得分：-1)

 Public Shared Function ValidEmailAddress(ByVal emailAddress As String, ByRef errorMessage As String) As Boolean
        If emailAddress.Length = 0 Then
            errorMessage = "E-mail address is required."
            Return False
        End If
        If emailAddress.IndexOf("@") > -1 Then
            If (emailAddress.IndexOf(".", emailAddress.IndexOf("@")) > emailAddress.IndexOf("@")) AndAlso emailAddress.Split(".").Length > 0 AndAlso emailAddress.Split(".")(1) <> "" Then
                errorMessage = ""
                Return True
            End If
        End If
        errorMessage = "E-mail address must be valid e-mail address format."
        Return False
    End Function
相关问题
最新问题