URL tagging and SEO

URL tagging is used by marketing professionals and web analysts to track online campaigns: email, PPC, affiliates, RSS feeds, you name. Any URLs that you can control and which are is sending visitors  to your site it’s recommended to be tagged. However, there are o couple of concerns regarding URL tagging and search engine optimization:

1. duplicate content – search engines will index tagged URLs as you can see further down
2. campaign tracking can be misleading
3. Page Rank leakage
4. 404 errors – landing people on a non existing URL after the campaign ended

Tagging means adding parameters to your URL so you can track the source, medium, campaign name, keywords and other metrics you need to analyze later on. Let’s say you have an email blast and you want to track the campaign’s performance.
By how the following results are you can see that this problem affects quite a few of the websites:
- there are 3.300.000 Google Analytics tagged URLs in Google’s Index
- there are 1.380.000 Google AdWords’ gclid URLs indexed in Google (not all will be tagged URLs thou)
If you want to dig deeper you can do a allinurl:{parameter ID} for other PPC engines, web analytics tool or email trackers. For those Here’s a list of parameters used by some major companies:
yahoo search marketing tags – ovraw, ovkey, ovmtc, ovadid, ovkwid
yahoo clickID – YSMWA
MSN clickID - msclkid
IndexTools – _s_ref
Omniture – a_aid, a_cid, a_did, s_kwcid
CoreMetrics – cm_ven, cm_cat, cm_pla, cm_ite
Webtrends – WT.cg_n, WT.cg_s, WT.mc_n, WT.mc_t, WT.mc_r, WT.ad, WT.ac
SalesForce parameters  - _kk _kt
Here are the issues explain in more details
1. Duplicate content
So, what you’d had as a link to your site like www.pistopmedia.com can look like http://www.pitstopmedia.com/?utm_source=vancouver&utm_medium=email&utm_term=seo%2Bvancouver&utm_campaign=emailB2c. The two pages are one and the same, and if search engines are somehow able to find that link, they might index that page and here you go, duplicate content issues.
2. Misleading campaign tracking
If your tagged URLs are picked up by search engines and ranked for particular terms, tracking the traffic coming from those keywords may become a mess. Your tracking parameters may override the search engines ones, and your analytics data will be corrupted.
3. Page Rank leakage
With your link building you should be consistent: always link to the same URLs for a page. Linking to pistopmedia.com and www.pitstopmedia.com is dividing you linking efforts.
Chances are low, but if someone is linking to your site using a tagged URL (copy an paste email from an email for example) your page rank will have to lose.
4. 404 Errors
Many times after a campaign ended, the URL become inactive. Therefore the risk of people bookmarking your tagged URLs then using them to come back on your site is quite eminent, at least for large sites.
As you can see these are only a few of the problems I could think of regarding tagged URL.
What we do for ourselves  is:
- to avoid duplicate content we use the rel=”canonical” tag on the tagged URL as well as noindex, nocache, nofollow directive with the robots meta tag
- the above will also keep us out of trouble for misleading campaign tracking from organic search results, since you are keeping those URL out of search engine index. If somehow some tagged URLs are getting indexed, you can request an URL removal within Google/Yahoo/Bing webmaster accounts
- we did 301 redirects from pitstopmedia.com of the site to www.pitstopmedia.com, as well as from www.pitstopmedia.com/index.php to www.pitstopmedia.com; basically you want to have a single URL for the same page
- to avoid the 404 errors, once a campaign becomes inactive, that URL is 301′d to www.pitstopmedia.com
One strategy we’ve seen is to do a 301 redirect of the tagged URLs to the root of the website even before the campaigns are done. 301 redirects are supposed to pass the header information, but that’s not 100% accurate and sometimes the referral data gets lost. This strategy has the advantage of displaying a clean nice URL so people will bookmark the SEO friendly URLs, but the trade off is with possible referral data.


What are your thoughts?