Traffic is generally a good thing for websites. But perhaps Pinterest, which has been called the third most popular social network after Facebook and Twitter, has enough.

Pinterest blocked traffic from Amazon and other websites on Black Friday last week, according to Pinfluencer, a Pinterest analytics service. Socialtimes reported today that extra holiday traffic — and suspected malicious activity — prompted Pinterest to refuse queries from the sites.

Update 9:38PM — Pinterest PR gave me the following statement:

During the holidays, we believe a third party was using Amazon Web Services to scrape our site so we temporarily blocked a specific traffic source, which is a common measure taken by web services. Some legitimate services may have been affected momentarily, but we do not believe that traffic to or from or other Amazon properties was impacted. 

Pinterest drives massive referral traffic that can drive impressive sales for online retailers. And though its growth has slowed in 2012, and the site is virtually ignored by small and medium-sized businesses, it is still on track to be the fourth-largest source of referral traffic on the web.

Amazon added Pinterest buttons to its website earlier this year (although it can be a massive where’s-Waldo exercise to find the social sharing buttons on Amazon’s busy pages). Presumably so many product pages were being viewed and shared by shoppers, Pinterest’s automated danger signals were activated.

The blockage lasted for 15.5 hours, from 11:30 PM on November 23th to 3PM on November 24th. Since Pinfluencer tracks pins, repins, likes, and comments, its services were affected as well.

I’ve contacted both Pinfluencer and Pinterest for more details, and will update this post as those companies respond.

photo credit: Thomas Hawk via photopin cc