The Tech Blog

Obfuscating email addresses

Posted by Charlie Harvey on Friday, January 23, 2009 1 comment

I guess this probably gets me the prize for being first to blog on New Internationalist’s new tech blog. And its a post about making life difficult for spammers. Yay!

I was just doing some work on the Clean Start pages, part of which was to add a mailto: link. Spammers are always scraping pages for mailtos, so I had a think about how one might obfuscate an email. The traditional way is name [at] site [dot] com. Or you could do like riseup and have a button in the way of any email addresses. But a quite cute technique (though not totally unbreakable) is to use html entities to encode your email address. For example, for the Clean Start email, I would do:

<a href=’&#109;&#97;&#105;&#108;&#116;&#111;&#58;&#99;&#108;&#101;&#97;&#110;&#115;&#116;&#97;&#114;&#116;&#64;&#110;&#101;&#119;&#105;&#110;&#116;&#46;&#111;&#114;&#103;’>Clean Start</a>

There’s an online tool which lets us do this. In the future it would be nice to add a filter to our CMS, Bricolage, that did this automatically when it hit a mailto link.


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Comments

Hi ho,

I dug up this sub-routine from another Bricolage-related template I had kicking around:

# obfuscated_mailto_link()
#
# How to use:
#
# obfuscated_mailto_link('joe@foo.com', 'Joe Schmoe');
# returns
# <a href="mailto:joe_att_foo_dott_com" onclick="$a='joe@f';this.href='mailto:'+$a+'oo.com';">Joe Schmoe</a>
#

sub obfuscated_mailto_link {

my ($orig_email, $visible_name) = @_;

my $munge = $orig_email;
$munge =~ s/\./_dott_/g;
$munge =~ s/\@/_att_/g;

my $pos = index $orig_email, '@';

my $chop1 = substr ($orig_email, 0, $pos+2);
my $chop2 = substr ($orig_email, $pos+2);
return <<EOF;

<a href="mailto:$munge"
onClick="\$a='$chop1';this.href='mailto:$visible_name <'+\$a+'$chop2>';"
onMouseOver="this.href='mailto:$munge'"
>$visible_name</a>
EOF
}


Wonder if we could put that into Typogrify, or a similar utility template, which would check for the presence of mailto links and convert them as described?

Phillip.

Phillip Smith on 02/05/2009 | view this user's profile
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