Making email addresses safe from bots on a webpage?

Question

When placing email addresses on a webpage do you place them as text like this:

joe.somebody@company.com

or use a clever trick to try and fo

Answer 1

This is what we use (VB.NET):

Dim rxEmailLink As New Regex("]*mailto:\b[^>]*>(.*?)")
Dim m As Match = rxEmailLink.Match(Html)
While m.Success
    Dim strEntireLinkOrig As String = m.Value
    Dim strEntireLink As String = strEntireLinkOrig
    strEntireLink = strEntireLink.Replace("'", """") ' replace any single quotes with double quotes to make sure the javascript is well formed
    Dim rxLink As New Regex("(]*mailto:)([\w.\-_^@]*@[\w.\-_^@]*)(\b[^>]*?)>(.*?)")
    Dim rxLinkMatch As Match = rxLink.Match(strEntireLink)
    Dim strReplace As String = String.Format("", _
                RandomlyChopStringJS(rxLinkMatch.Groups(1).ToString), _
                ConvertToAsciiHex(rxLinkMatch.Groups(2).ToString), _
                rxLinkMatch.Groups(3), _
                ConvertToHtmlEntites(rxLinkMatch.Groups(4).ToString))
    Result = Result.Replace(strEntireLinkOrig, strReplace)
    m = m.NextMatch()
End While

and

    Public Function RandomlyChopStringJS(ByVal s As String) As String
        Dim intChop As Integer = Int(6 * Rnd()) + 1
        Dim intCount As Integer = 0
        RandomlyChopStringJS = ""
        If Not s Is Nothing AndAlso Len(s) > 0 Then
            For Each c As Char In s.ToCharArray()
                If intCount = intChop Then
                    RandomlyChopStringJS &= "'+'"
                    intChop = Int(6 * Rnd()) + 1
                    intCount = 0
                End If
                RandomlyChopStringJS &= c
                intCount += 1
            Next
        End If
    End Function

We override Render and run the outgoing HTML through this before it goes out the door. This renders email addresses that render normally to a browser, but look like this in the source:

Obviously not foolproof, but hopefully cuts down on a certain amount of harvesting without making things hard for the visitor.