ASP mail form

Posted on 2014-03-07
Medium Priority
Last Modified: 2014-03-16
Dear Experts,

I have a web page that allows visitors to complete a form and send the information to our support email address. We have been getting a lot of spam, most of which contains URL's.

What is the best way to detect the presence of "http://" in a field and silently not send the email without giving an error message? I have tried using the Instr function but I don't think I am using it correctly.

Question by:ttobin333
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LVL 33

Expert Comment

by:Big Monty
ID: 39914066
Easiest and most common way would be to use captcha
LVL 58

Expert Comment

ID: 39914077
Is there a possibility that real people may send you a link? If so your logic would be bad.
But anyway these are bots not real people, they don't care if it seems like the email was sent - follow Monty's advice and you will eliminate 99% of this
(no points for this)

Author Comment

ID: 39914179
Thanks, guys.

My software also uses the same page to send automated license registration notifications, so I would need to be able to bypass the Captcha with a "secret switch". Any suggestions on that?

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LVL 33

Expert Comment

by:Big Monty
ID: 39914183
either create a condition where the captcha only appears after a given condition...


move your notification logic to it's own page.

I would probably choose the latter option if it's not a huge undertaking. Separating different bits of functionality is a lot easier to maintain than if everything is dumped in to one page
LVL 53

Assisted Solution

by:Scott Fell, EE MVE
Scott Fell,  EE MVE earned 1000 total points
ID: 39914487
For small sites it really does not take much to ward off the annoying spammers.  When I try and implement a traditional style captcha, then the client complains that it is too hard to read but the spam goes away...and they typically will say their response goes away too because of the captcha.  

What I ended up doing on a number of sites is using something very simple and you can implement on one page and is easy to read.  It is not best practice by any means but for small sites I was able to eliminate 100 rapid fire spams to maybe 1.  

For an added bonus, you could add a session("submitCount")=0 and each time the form gets submitted add 1.  If the session("submitCount") goes past 3 or 4, hide the form.  If the form is successful, set session("submitCount")=0

And the double added bonus, I use a free webservice that converts the IP to a location
http://smart-ip.net/geoip-xml/"&request.ServerVariables("REMOTE_ADDR") and in the notes that get sent to the client include the info from the webservice which includes the country and city and state.  This has been helpful when humans fill out forms from high spammer countries.

This was the best happy medium I came up with that prevented the rapid fire spambot's and was mostly easy to read and understand making the client's happy.

Dim max,min,theNumber,codeNumber, errorText
function getCaptcha()
'*** Make a random number 1 to 7 ***
	'*** pair number and word ***
	select case cstr(theNumber)
		case "1"
		case "2"
		case "3"
		case "4"
		case "5"
		case "6"
		case "7"
	end select
end function

if request.form("something")<>"" then '*** form is submited ***
	' *** Test to see if captcha is correct
	if request.form("code")=session("captcha") then '*** ok to process ***
		' update your database 
		errorText="Please enter the secret code"
		strSomething=request.form("something")'*** prefill in the form ***'
	end if
strCaptcha=getCaptcha() '*** create new capcha ***
	strCaptcha=getCaptcha() '*** create new capcha ***
end if
'*** set the captcha ***
arrCaptcha=split(strCaptcha,",") ' *** convert comma seperated pair to an array ***
codeNumber=arrCaptcha(0) ' *** Array's start at zero | 1,2,3... ***
session("captcha")=arrCaptcah(1) ' *** one,two, three...


<% if errorText<>"" then 'make this box red or yellow %>
<div class="error"><%=errorText%></div>
<%end if%>
	<input name="something" value="<%=strSomething%>">
	<div>Select the secret code:<%=codeNumber%></div>
	<select name="code">
		<option value="zero">Select Code</option>
		<option value="one">One</option>
		<option value="Two">Two</option>
		<option value="Three">Three</option>
		<option value="Four">Four</option>
		<option value="Five">Five</option>
		<option value="Six">Six</option>
		<option value="Seven">Seven</option>
<button type="submit">Submit</button>


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LVL 58

Expert Comment

ID: 39914807
You'll find that reCaptcha is actually easier to use these days and invariably you'll get an easy to read image (if they suspect you are a bot they will send an harder to read image).
I find most times I get just a few numbers to type in.

Author Comment

ID: 39915061
Can you assist with the ASP code for Captcha?
LVL 58

Expert Comment

ID: 39915063
They have samples/'what to do' on the site when you register
LVL 33

Expert Comment

by:Big Monty
ID: 39915066
here's a pretty straightforward example:

LVL 33

Accepted Solution

Big Monty earned 1000 total points
ID: 39915068
if you're still hesitant to do captcha, you may want to look at this approach:


Author Closing Comment

ID: 39932611
Very helpful, thank you!

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