The Usage of CAPTCHAs for Submissions
The original motivation behind submission credits started off with the sharp rise in the number of sites that introduced a CAPTCHA into the submission process. During the testing phase we called these Captcha credits.
In case you're not aware, a captcha is usually a graphic image containing words or a random sequence of letters & numbers which are designed to be readable by humans but not by computers. Thus computer software that tries to submit to these sites (like IMAutomator) cannot read the graphic and hence cannot submit to the site.
When we first started IMAutomator only a handful of sites used these captcha mechanisms so we simply ignored those and used the rest. But over time the balance has shifted towards captchas being the norm. Nowadays if we have a list of 50 new potential sites, we're lucky if there's a single site that allows a submission without some form of captcha.
It's for this reason that we've previously found it difficult to keep the number of supported sites high. As sites die - and they always do, this is the Internet... we'd struggle more and more to find replacements as all the new sites being built were using captchas and we couldn't support them.
Enter Captcha Recognition Services
There are many types of software that automate submission to web forms for one purpose or another so the need to automate the recognition of these captchas grew. With demand there comes supply and a few companies started to pop up that could recognise these captchas for you (using real people to do the recognition)... for a fee. It was this fee which blocked us from using these services in IMAutomator.
Until a year ago we were running a free service which had tens of thousands of members who were submitting around 100k links per day! This was quickly growing out of hand and we had to put in measures to stem the flow and eventually in February 2012 we discontinued the free service and replaced it with the Light service.
We toyed with the idea of incorporating support for one of these services into IMAutomator for a few months. Initially we were going to require members to have their own account at the service and give us the username and password but we soon dismissed that as it was messy and required the member to spend more money!
Instead we decided that we'd use the service using our own account but we'd still need to limit the usage of these sites because the sheer volume of links that are posted by IMAutomator would wipe out our business if we absorbed all the cost! So we came up with the idea of credits which are allocated to members on a monthly basis and could be spent on submissions of the members choosing. By controlling the number of credits we give away, we can absorb that cost and finally include all these captcha sites into our system!
The Spam Reduction Side Effect
We have implemented some strict measures into the system to prevent spam from being submitted but there is a fine line between blatant spam (such as porn) and not-quite-spam-but-definitely-low-quality content such as profile pages, pages with nothing but adverts and so on.
We have many wonderful members with high quality websites that use IMAutomator to submit great content and we love that as it's a win-win all around. The sites we submit to get great content, the members get backlinks and we get paid! However, due to sheer of volume of links that can be submitted - 10 links per day x 15 sites even for a Light membership, there are some members that submit all sorts of low quality content.
Now this isn't exactly spam and we don't block it because it's perfectly fine for a large number of bookmark sites. But it simply will not make the cut on those high profile, high traffic, human edited sites. People sometimes ask us why we don't have sites like Digg or Reddit in our system - this is why. Our accounts would be blocked within 24 hours if we allowed the usual submissions to get posted to these sites.
But using a credit system, and in particular by making the higher PR sites cost more credits, has the side effect of coaxing members towards submitting only their best content to the credit sites with the highest PR. We would hope that not many members would spend 7 or 8 credits to submit a meaningless about page to a single site!
So, with this credit system now in place, as well as using it for all sites that use a captcha, we will also use it for higher profile sites that are picky about submissions to encourage only the best quality content for those sites.