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Anti-spam techniques for web pages?

JW
I'm putting together a bulletin board system for a community that allows folks
to put up for sale postings, notices, etc. These notices usually include the
posters' email addresses.

A similar posting service which I use is in place in another town and I do
occasionally get spam from my notices (not a lot, usually 419 spam.)

This is a free system and doesn't require a login, and I want to avoid/minimize
the possibility of spammers from harvesting these addresses while at the same
time maintaining the mailto: links.

Basic requirements are 1) easily automated when I create the posting pages
(MySQL->PHP->HTML) and 2) maintain user convenience (clickable links regardless
of browser, usable by sight impaired readers, ...)

But should I even bother? Is there anything that is even partially effective
against harvesting bots? Is there a tried and true obfuscation method that I can
use?

Thanks!
--
jwayne@_myrealb ox_no_spam.com
Jul 20 '05 #1
25 4328
See http://www.cdt.org/speech/spam/030319spamreport.shtml
and http://www.wbwip.com/wbw/emailencoder.html

In my experience, newsgroups are the biggest exposure!

--
############### #######
## PH, London ##
############### #######

"JW" <jwayne@_myreal box_no_spam.com > wrote in message
news:qi******** *************** *********@4ax.c om...
I'm putting together a bulletin board system for a community that allows folks to put up for sale postings, notices, etc. These notices usually include the posters' email addresses.

A similar posting service which I use is in place in another town and I do
occasionally get spam from my notices (not a lot, usually 419 spam.)

This is a free system and doesn't require a login, and I want to avoid/minimize the possibility of spammers from harvesting these addresses while at the same time maintaining the mailto: links.

Basic requirements are 1) easily automated when I create the posting pages
(MySQL->PHP->HTML) and 2) maintain user convenience (clickable links regardless of browser, usable by sight impaired readers, ...)

But should I even bother? Is there anything that is even partially effective against harvesting bots? Is there a tried and true obfuscation method that I can use?

Thanks!
--
jwayne@_myrealb ox_no_spam.com

Jul 20 '05 #2
JW wrote:
I'm putting together a bulletin board system for a community that allows folks
to put up for sale postings, notices, etc. [...]
This is a free system and doesn't require a login, and I want to avoid/minimize
the possibility of spammers from harvesting these addresses while at the same
time maintaining the mailto: links. [...]


I've had a good deal of success using character encoding to obfuscate
email addresses. HTML allows "&#xxx;" as a substitute for a character
where 'xxx' is the appropriate number (usually the ASCII code).

<A href="mailto:wi llondon@bigfoot .com">
willondon@bigfo ot.com</A>
uses 'mailto' to send to 'w********@bigf oot.com'.

Advantages:
(1) easy to program;
(2) seems to work with all browsers and email clients I've tried; the mail
client opens a compose window with the correct (uncoded) address in the
'To:' field;
(3) I have two pages, published for over 6 years, where I'm sure I've
never used the address anywhere else, and have yet to receive spam to
those addresses.

Disadvantages (apart from 'mailto' inherent disadvantages):
(1) from autumn 2002, I've read reports that scumbots are now decoding
these addresses;
(2) even 6 years ago, it seemed that ultimately, it's harvestable, and I'm
very surprised that I've had as much success as I have; not guaranteed to
last forever.

If you make an email address visible to a browser or mail client, it *has*
to be visible to a scumbot, too. There's no way around that.

A common approach is to not publish the address, but use CGI or other
server-side programming to take care of inputting the message and mailing
it; but you might consider this too much processing.
Hope that helps,

--
Willondon
Jul 20 '05 #3
JW wrote:
I'm putting together a bulletin board system for a community that allows folks
to put up for sale postings, notices, etc. These notices usually include the
posters' email addresses.
This is a free system and doesn't require a login, and I want to avoid/minimize
the possibility of spammers from harvesting these addresses while at the same
time maintaining the mailto: links.


The techniques mentioned in other posts, such as using URL encoding or numeric
entities in the email address, prevent harvesting of information by simple bots, and
most of today's bots are simple because they get enough email addresses using simple
techniques and don't bother going for the difficult ones. As more people make their
email addresses harder to extract, this may change.

If you could replace the mailto links with a Web form for sending messages, you
could display only partial email addresses like "jwayne@myrealb ..." and keep the
full email address in your database instead of displaying it on the Web page.

--
Klaus Johannes Rusch
Kl********@atme dia.net
http://www.atmedia.net/KlausRusch/
Jul 20 '05 #4
I use a technique which uses JavaScript to assemble the email address on the
fly. Users with JavaScript disabled get a warning. I also use the @
code instead of @. The JavaScript is in a function loaded from a separate
file.

However, even these paranoid eccentricities may be in vain. I have a domain
with a default forwarding, so I can make up email addresses on the fly.
I've spotted spam arriving less than an hour after first use of a new
address, so someone is using a packet sniffer somewhere.

Hanging's too good for them.

--
############### #######
## PH, London ##
############### #######

"Klaus Johannes Rusch" <Kl********@atm edia.net> wrote in message
news:3F******** *******@atmedia .net...
JW wrote:
I'm putting together a bulletin board system for a community that allows folks to put up for sale postings, notices, etc. These notices usually include the posters' email addresses.
This is a free system and doesn't require a login, and I want to avoid/minimize the possibility of spammers from harvesting these addresses while at the same time maintaining the mailto: links.
The techniques mentioned in other posts, such as using URL encoding or

numeric entities in the email address, prevent harvesting of information by simple bots, and most of today's bots are simple because they get enough email addresses using simple techniques and don't bother going for the difficult ones. As more people make their email addresses harder to extract, this may change.

If you could replace the mailto links with a Web form for sending messages, you could display only partial email addresses like "jwayne@myrealb ..." and keep the full email address in your database instead of displaying it on the Web page.
--
Klaus Johannes Rusch
Kl********@atme dia.net
http://www.atmedia.net/KlausRusch/

Jul 20 '05 #5
In article <3F************ ***@atmedia.net > in
comp.infosystem s.www.authoring.html, Klaus Johannes Rusch
<Kl********@atm edia.net> wrote:
If you could replace the mailto links with a Web form for sending messages, you
could display only partial email addresses like "jwayne@myrealb ..." and keep the
full email address in your database instead of displaying it on the Web page.


I _hate_ those forms. If I'm sending mail, I want to use my mailer.
It has things like spell checking and the copy-to-self feature. And
half the time I type a message into those forms and then nothing
happens when I click 'send'.

--
Stan Brown, Oak Road Systems, Cortland County, New York, USA
http://OakRoadSystems.com/
HTML 4.01 spec: http://www.w3.org/TR/html401/
validator: http://validator.w3.org/
CSS 2 spec: http://www.w3.org/TR/REC-CSS2/
validator: http://jigsaw.w3.org/css-validator/
Jul 20 '05 #6
"Philip Herlihy" <fo******@REMOV Eherlihy.eu.com > wrote in
news:be******** **@hercules.bti nternet.com:
I use a technique which uses JavaScript to assemble the email address
on the fly. Users with JavaScript disabled get a warning.


A slightly better approach(in my opinion) is what we do on our
'Contact Us' page:
http://www.confluence.org/contact.php
With javascript enabled, you'll get mailto links, but the
email addresses aren't in a readable format in the source.
If javascript is disabled, you'll see the email addresses,
as images(no good for 'cut & paste", but at least they are available).

--
Dave Patton
Canadian Coordinator, the Degree Confluence Project
http://www.confluence.org dpatton at confluence dot org
My website: http://members.shaw.ca/davepatton/
Vancouver/Whistler - host of the 2010 Winter Olympics
Jul 20 '05 #7
Neat!

--
############### #######
## PH, London ##
############### #######

"Dave Patton" <dp*****@remo ve-for-nospam.confluen ce.org> wrote in message
news:Xn******** *************** *******@24.71.2 23.159...
"Philip Herlihy" <fo******@REMOV Eherlihy.eu.com > wrote in
news:be******** **@hercules.bti nternet.com:
I use a technique which uses JavaScript to assemble the email address
on the fly. Users with JavaScript disabled get a warning.


A slightly better approach(in my opinion) is what we do on our
'Contact Us' page:
http://www.confluence.org/contact.php
With javascript enabled, you'll get mailto links, but the
email addresses aren't in a readable format in the source.
If javascript is disabled, you'll see the email addresses,
as images(no good for 'cut & paste", but at least they are available).

--
Dave Patton
Canadian Coordinator, the Degree Confluence Project
http://www.confluence.org dpatton at confluence dot org
My website: http://members.shaw.ca/davepatton/
Vancouver/Whistler - host of the 2010 Winter Olympics

Jul 20 '05 #8

"Stan Brown" <th************ @fastmail.fm> wrote in message
news:MP******** *************** @news.odyssey.n et...
In article <3F************ ***@atmedia.net > in
comp.infosystem s.www.authoring.html, Klaus Johannes Rusch
<Kl********@atm edia.net> wrote:
If you could replace the mailto links with a Web form for sending messages, youcould display only partial email addresses like "jwayne@myrealb ..." and keep thefull email address in your database instead of displaying it on the Web
page.
I _hate_ those forms. If I'm sending mail, I want to use my mailer.
It has things like spell checking and the copy-to-self feature. And
half the time I type a message into those forms and then nothing
happens when I click 'send'.


I've actually begun getting more contact from my website after converting to
contact form only.
The number of new website contacts is exponentially higher than before.
--
Karl Core

Charles Sweeney says my sig is fine as it is.
Jul 20 '05 #9
In article <3F************ ***@atmedia.net > in
comp.infosystem s.www.authoring.html, Klaus Johannes Rusch
<Kl********@atm edia.net> wrote:
One option might be to not
show the email address but let you retrieve the email address by having it sent to
your address, so you can then use your mailer to respond.


How many people do you think are willing to jump through such hoops?
If even 10% refuse (or can't figure out your scheme), that's 10% of
sales lost.

--
Stan Brown, Oak Road Systems, Cortland County, New York, USA
http://OakRoadSystems.com/
HTML 4.01 spec: http://www.w3.org/TR/html401/
validator: http://validator.w3.org/
CSS 2 spec: http://www.w3.org/TR/REC-CSS2/
validator: http://jigsaw.w3.org/css-validator/
Jul 20 '05 #10

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