As an SEO professional I am constantly focused on tracking sources of website visitors, but not all sources of traffic are good. In fact, some are malicious. Referral spam web sites, like and more recently, are designed only for self-promotion purposes for those sites themselves, but in their behavior, they give site owners the false sense of security that their sites are suddenly much more popular. And while you may think you’re suddenly getting more traffic, they also average down other critical web site performance metrics.

You may be noticing steady increases in “sessions” (visits) to your site, but spam referrers don’t stay on a site for long nor do they visit multiple pages. You will notice a converse negative change to key metrics like your “Bounce Rate,” “Pages / Session” and “Average Session Duration.” More visits that don’t stay on your site, visit multiple pages or ultimately do not convert (do what it is you want them to do) are no more than the equivalent to eating empty calories. Basically, they are worthless visits to you when trying to assess what is working or not on your web site.

Referrer Bombing Skews Your Visitor Metrics

Referrer bombing is a form of “spamdexing” aimed at improving the search engine performance of the site conducting the spamming. Most sites that do this try to fly under the radar. Others, like Semalt, have web pages set up with explanations trying to rationalize their intent as a legitimate directory trying to benefit the victim (you). It’s just utter B.S.

Bogus Referral Traffic Skewing Site Visitor Data

If you’re not paying attention to the details of your site visitor data, at the surface the referral traffic you are suddenly receiving makes you feel really great about yourself. “Hey!” you think to yourself, “My SEO efforts are really paying off. I must be an SEO god or something!” But if you do a little digging, you’ll quickly discover the humbling reality. You’re just getting bombed by a bogus referral site. How do you find out?


Look in your Google Analytics account and study the “Acquisition” section of data. Within that section, look at the Referral sources. If you see visits being recorded from Semalt,,,,, (and hundreds of others like them) then your site is being attacked by referrer bombing sites, and the visits are doing nothing but negatively skewing real site activity from actual human visitors. Be sure to research each of the domains you find and you’re not familiar with to ensure it is indeed a referral spammer offender. You can Google the name and look for complete lists of spam referrers.

While on one hand, your visits in a particular period are bolting upward, the visits are incredibly short and typically only hit one page. So the effect is that your average time per session and pages per visits statistics are being negatively skewed. Bounce rates skyrocket too. So if you’re an SEO manager having to prove to a boss or client that the site performance is improving, you’re dealing with data you have to filter out.

How to Filter Referral Bombing Data from Your Google Analytics

There are a number of ways to address referral bombing sites. Among the easiest and fastest to mitigate the site visitor data skewing issue is to create filters in your Google Analytics admin area. Filters can be used to block (aka not count) traffic from specific IP addresses or domains from counting in your analytics.

If you’re not familiar with the filter capabilities in Google Analytics, chances are your site traffic statistics are not just skewed by referral spammers, but by visits to your site you make yourself, visits from your staff, family, consultants, and others who are not likely to actually conduct commerce through your site. You should really be filtering them by IP address, but that is for another lesson.

To block referral bombers’ traffic from skewing your data, do the following simple steps, assuming you are using Google Analytics:

  1. Log into your Google Analytics account
  2. Depending upon how your home panel loads, look across the top for the Admin tab. Click “Admin.”
  3.  There will be 3 columns in the default Admin tab. Look to the right column called “View,” and down the list, click “Filters.”
  4. Click the red button, “New Filter.”
  5. Keep the “Create new filter” radio button toggled (that’s the default).
  6. Create a name. I use the name of the site followed by a description or an acronym for the type of filter I’m going to create. Since most of these are domain based filters we’re creating, I would call a filter block “semalt domain.” Whatever floats your boat but make it so you don’t have to open the filter to remember what the filter is blocking is what I’m suggesting.
  7. For Filter Type, you can use a predefined filter.
  8. Select “Exclude.”
  9. From “Select Source or Destination,” choose “traffic from the ISP domain.”
  10. From “Select Expression,” you can choose “that are equal to,” or “that contain.”
  11. Grab the entire URL of the offending web site and enter it the field that is revealed under “ISP Domain.”
  12. Click “Save.” BOOM! Done!

There are a couple of other elements you can fill out or play with, but that’s the basic gist of the process to block. Just be sure to repeat this process for each of the offending referral spammers.

 Frustrate Spam Referrers Before They Hit Your Site

There are other steps you can take to try to block the unwanted visit before it hits your site. One is to use your .htaccess file to block those sites from seeing your site’s pages. To do this, open your .htaccess file with a standard text editor and add the following:

<FilesMatch “(.*)”>
Order Allow,Deny
Deny from
Allow from all

Replace the IP address to the IP of the offending website. This will return a 403 Forbidden server error instead of your site files to anyone (or anything) trying to visit your site. You’ll have to do this repeatedly for each IP you want to block. Keep in mind, you may be updating this list regularly (just like adding the Filters). Your .htaccess file can get big fast. Also, be sure the IP address you’re blocking is accurate. You don’t want to accidentally deliver 403 errors to visitors you actually want.

Referral spam and spam bombing of web sites has been going on for years. It seems to be getting worse or at least more gratuitous lately. Blocking them can be a daunting task that won’t really ever end. But do your best to filter them from your analytics so that the data your assessing about your site visitors is as accurate as possible. There are so many valid opportunities to learn valuable marketing insights from healthy site traffic. Do your best to ensure your Google Analytics data tells the most accurate story possible.

Good luck!


Erik is the Founder and President of FOSSmg (Foss Marketing Group, Inc.), a full service online marketing and advertising agency specializing in web site design, social media marketing, search engine optimization, pay per click advertising, email marketing, branding, design, and marketing research.

Founded in 2001, Erik spends each and every day providing great companies, small and large from around the globe with excellent marketing and advertising solutions…solutions that make an impact.

Erik is also a husband, a father to four amazing children, an avid sports fan, movie fan, and has spent much of his life playing, singing, writing and recording original rock music.

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