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Visual Basic Code > Validating An Email Address

Validating An Email Address

Public Function Validate_EmailAddress(ByVal EAddress As String) As Boolean
    'Dimension Variables.
    Const AllowChars = "1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ" + _
     "abcdefghijklmnopqrstuvwxyz._-"
    Dim UserName As String
    Dim ServerName As String
    Dim x As Long
    
    'Validate email address.
    x = InStr(1, EAddress, "@")
    If x = 0 Then GoTo BadAddress
    If InStr(x + 1, EAddress, "@") > 0 Then GoTo BadAddress
    UserName = Left$(EAddress, x - 1)
    ServerName = Right$(EAddress, Len(EAddress) - x)
    If Left$(UserName, 1) = "." Or Right$(UserName, 1) = "." Then GoTo BadAddress
    If Left$(ServerName, 1) = "." Or Right$(ServerName, 1) = "." Or _
     InStr(1, ServerName, ".") = 0 Then GoTo BadAddress
    For i = 1 To Len(UserName)
        If InStr(1, AllowChars, Mid$(UserName, i, 1)) = 0 Then GoTo BadAddress
    Next
    For i = 1 To Len(ServerName)
        If InStr(1, AllowChars, Mid$(ServerName, i, 1)) = 0 Then GoTo BadAddress
    Next
    Validate_EmailAddress = True
    Exit Function

BadAddress:
    Validate_EmailAddress = False

End Function