Update February 2010 Google no longer honors the nofollow tag! Instead of protecting the PR/link benefit it used to conserve for non nofollow links, it now DELETES the PR/link benefit! Stupid move by Google as it again forces webmasters to look for alternatives to nofollow to protect PR/link benefit when linking to sites we do not wish to promote!
My advice do not use rel=”nofollow” on any website if you care about search engine optimization. To get around this issue I created a SEO WordPress Theme that instead of using normal links to link to comment authors URLs it uses form button links (Google ignores them, no wasted PR/link benefit).
WordPress Comments and rel=nofollow
New WordPress installations by default now use the rel=”nofollow” attribute on comment links. If you are not familiar with rel=”nofollow” earlier this year the major search engines (Google, Yahoo etc…) issued a new rel attribute (nofollow) which when used on a text or image link will tell the major search engines to not consider this as a link that should pass link benefit (or PageRank in Google’s case).
Link benefit or PageRank is very important to Google and to a lessor degree Yahoo and MSN search engine rankings, so adding rel=”nofollow” to a link will mean the recipient page will not gain an advantage in the major search engines.
Text links and PR are a major part of search engine optimization, without links (PR) a web site is highly unlikely to do well in Google for anything but the easiest SERPs. This has led to many webmasters willingness to resort to dubious (unethical SEO practices such as blog comment link spamming (I’ve done it in the past).
If you’ve owned a blog that allows comments and to a lessor degree pings/trackbacks for more than a week or two you’ll already know what comment SPAM is. If not webmaster add comments to blogs for a link to their own website(s), that in itself isn’t a problem, but the comments tend to not reflect the content on the blog page, usually comments like “great site” or just a bunch of porn or phone sex text links! Comment SPAM started with individuals posting the comments manually, but now it’s mostly a set of scripts that scan the Internet for open comment pages to SPAM. This blog has had almost 4,000 SPAM comments, almost all caught by various WordPress plugins, so comment SPAM is a major problem for bloggers worldwide!
According to Akismet http://akismet.com/ the vast majority of blog comments are SPAM, 92%!!!

My experience of owning blogs agrees with the above, most comments are indeed SPAM :-( So I fully understand why the WordPress developers have taken this step due to the plethora of blog comment SPAM currently plaguing the blogosphere, but it comes at a cost to WordPress users, real commenter’s no longer get a link back to their site and this is bad for blogging!
The good news is if you are a WordPress user there are tools (plugins) that almost stop all comment SPAM (especially automated comments which are the biggest problem). Like I said above this blog has seen almost 4,000 spammed comments-

Yet only a couple of manually spammed comments got through, so the tools I use work at filtering SPAM.
List of Comment Filtering Plugins
Akismet http://akismet.com/ – Akismet checks your comments against the Akismet web service to see if they look like spam or not. You need a WordPress.com API key to use this service. You can review the spam it catches under “Manage” and it automatically deletes old spam after 15 days.
Spam Karma 2 http://unknowngenius.com/blog/wordpress/spam-karma/ – Ultimate Spam Killer for WordPress. The proud successor to Spam Karma, with whom it shares most of the development ideas, but absolutely none of the code. It is meant to stop all forms of automated Blog spam effortlessly, while remaining as unobtrusive as possible to regular commenter’s.
Bad Behavior http://www.homelandstupidity.us/software/bad-behavior/ – Deny automated spambots access to your PHP-based Web site.
Bad Behavior stops most SPAMbots at source, they don’t even get a chance to try to SPAM a blog (this saves a lot of time double checking that filtered SPAM is actually SPAM, basically less to check). The ones that get through (not many) are then handled by Akismet and Spam Karma 2 (they do the same thing, well). These two plugins filter the remaining SPAMMED comments, but doesn’t immediately delete them (deleted 15 days later), giving you a chance to recover any posts that are not SPAM (it happens).
You may ask why use both Akismet and Spam Karma 2 if they both do the same thing? Well recently one of them went down recently and thousands of WordPress blogs got a lot of SPAM, since I run the two plugins my blogs remained SPAM free.
I’m that happy with the SPAM filtering that I’ve removed the rel=”nofollow” attribute from comments on this blog and if it goes well will do the same on my other blogs. If you’d like to remove rel=”nofollow” from your blog it’s quite easy.
Removing rel=”nofollow” from comments from a WordPress blog
Find the file
comment-functions.php
In the folder
/wp-includes/
Look for this (around line 360).
$return = “<a href=’$url’ rel=’nofollow’>$author</a>”;
And change to-
$return = “<a href=’$url’>$author</a>”;
Save the file and upload to your sites server. The Authors comment links will no longer have the rel=nofollow attribute. Links within the body of the comment will still have the nofollow attribute added, might remove that if this works out well.
My only concern is manual comment SPAMMERS now, but I don’t think it will be a major problem (time will tell).

15 responses to WordPress Comments and rel=nofollow
Have you had any problems with spammers yet?? Just wondering – I implemented this on my blog a few minutes ago. Thanks for the tip!
(I think it’s actually kind of rude to keep that attribute in there. Commenters are bloggers a favour by participating in our blogs, the least we could do is give them a followable linkback. Abuse might be more of a problem with high profile blogs but stil…)
WordPress Comments and rel=nofollow
Hey Megan,
Difficult to say as this blog had the highest SPAM rate of all sites I own put together and then the others don’t come close (have quite a few WordPress Blogs as well). When I made this post Akismet had caught almost 4,000 SPAM comments, now it’s at 6,067 so 2,000 SPAM comments in 3 months!!
Relatively speaking that’s an increase, but it could be because the site is more popular since adding free WordPress themes with AdSense and SEO optimisation included. So the increase could be due to popularity.
I have noticed one spammer to my blogs, presumably owns gameburn.org (that’s the SPAMMED link) and daily I’m finding thought out SPAM that at first got through. Turned out he/she has been copying content from other sources (forums) and posting it as comments for backlinks.
Looks like all the posts are getting filtered now, so Akismet has learned this poster is a spammer.
Had the posts just been to this blog I might have believed it was targeted since I removed the nofollow, but it’s on other blogs with the nofollow still part of comments. So though SPAM might have increased I’ve not noticed SPAM that’s not automated which was my only concern at trying this. Still early days though.
David
WordPress Comments and rel=nofollow
I’ve had some good luck with both Akismet and Spam Karma, but Spam still sneaks through from time to time. I keep my comments moderated, so nothing hits the site without approval.
Akismet does do a great job of filtering spam. I find that it works very well on my WordPress sites.
I’ve given up on Akismet for Drupal sites however. It really slows down the commenting process for visitors. I assume this is due to how it is implemented in Drupal.
I’ll try Bad Behaviour on your advice. I get so much spam caught by Akismet that I’ve given up going through it all looking for false spam.
I’m just looking into removing rel=nofollow from my blog. Part of blogsphere is supporting other blogs, and I think that rel=nofollow throws the baby out with the bathwater, and does nothing to reduce spam.
WordPress Comments and rel=nofollow
Hi David,
thanks for this very precise explanation for the various possibilities to effectively fight spam. We have had our share of spam and I have therefore just installed the updated version of spam karma which i found to be the perfect companion to akismet. Hopfully this will reduce the amount of spam we have experienced on our blog drastically, as it is very timeconsuming to clean out the comments-section by hand.
Thanks again,
Steve Riehler
WordPress Comments and rel=nofollow
I’m going to install the “dofollow” plugin: do you think it would be nice to start a “dofollow campaign” for all the blogs of the world? I wasn’t aware of this trick before, thanks.
Thanks for the post, I believe in moderation and filtering andnot penalizing good commentors because of a few bad apples.
Just a note: If you’re using WordPress 2.1.2, removing nofollow is a little different.
Find the file…
/wp-includes/comment-template.php
and around line #48 make the same changes you have posted above.
Cheers !!!
WordPress Comments and rel=nofollow
Hy Dave, thanks a lot: at the end I found this dofollow plugin http://www.semiologic.com/software/dofollow/ and I have installed it!
Nice post. I’m running Akismet on my site but lately I’ve been having 1 or 2 spam comments slip through per day and marking them as spam is messing up the RSS feed for my readers (it ends up showing everything in the feed as new) so I’ve been looking for something to augment it.
The “Bad Behavior” plugin you mentioned sounds like exactly what I want but the link is dead. Do you happen to have a copy you could post?
WordPress Comments and rel=nofollow
It’s working now http://www.bad-behavior.ioerror.us/download/
David
thanx for this post,since my Akismet stopped,i’m getting much spam!
I like WordPress,it’s my kind of thing.I have my own blog on it.
i would love to use akismet but i still need to register to WP.com to get the api key
How can 92% of comments be spam? If this is the case, why do we even keep comments on our blogs? And i know the no follow is to fix things, but I believe it’s still used by google. Let’s try :-)
Moderator: This was picked up as SPAM, removed the link and let it through :))
WordPress Comments and rel=nofollow
You should add SpamTask to the list. I think it works best of all the anti-spam plugins.
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