What are doorway pages? Google's guidelines specify them as: 

“…typically large sets of poor-quality pages where each page is optimized for a specific keyword or phrase. In many cases, doorway pages are written to rank for a particular phrase and then funnel users to a single destination. Whether deployed across many domains or established within one domain, doorway pages tend to frustrate users, and are in violation of our webmaster guidelines.”

How do doorway pages accomplish the funneling of traffic?  Doorway pages are often “cloaked,” which is a method used to deliver a version of the doorway page to a visitor that is different from what a web crawler sees. Using the IP address of the visitor, a script can determine whether the visitor is a user browser or a search engine spider. The information delivered to the search engine contains an optimized, keyword-rich “cloaked" doorway page to deceive the search engine (that may end up ranking highly in search engine results), which is different than what users actually see.

Using doorway software and keyword lists, a SEO firm can create hundreds of auto-generated “doorway” pages that are misleading and are a means to funnel traffic to another URL, which usually does not accurately reflect the visitor’s search.

The use of doorway pages is usually considered spam, or “spamdexing,” since they are created specifically for indexing into search engines and web crawlers. 

Do doorways help with SEO? 

It is best to not use doorways to your website as an SEO tool. An important reason for this avoidance is that if a visitor encounters a doorway page that does not fit their search terms accurately, it is most likely that they will hit their “Back” button and never explore the actual site. Thus, a doorway may generate a number of hits, but very few actual interested users and even fewer, if any, actual sales. 

If you want to focus and direct traffic to your website or certain parts of your website, rather than create a doorway, it is better to optimize the targeted landing web pages so that they show up on search results. As an example, say you run a website for both computer sales and repair. Rather than create “doorway” pages for "computer sales" keywords and "computer repair" keywords that redirects to your home page, you could set up each section of your website to optimize specifically for “computer sales” searches and “computer repair” searches. 

Secondly, doorway pages could actually result in your website being completely removed from search engine results. Search engines are constantly removing doorway pages from its index if they feel the doorway is deceitful or the intention is deceptive. Some search engines will also remove the linking websites. That could mean your actual website could suffer from potential future searches and face a steep uphill climb to get re-included with search engine indexing. This also means that you should not link directly to a doorway from your website. 

Google has published their stance on doorway pages as follows:

“Avoid 'doorway' pages created just for search engines, or other 'cookie cutter' approaches such as affiliate programs with little or no original content…

…trying to deceive (spam) our web crawler by means of hidden text, deceptive cloaking or doorway pages compromises the quality of our results and degrades the search experience for everyone. We think that's a bad thing.

…If an SEO creates deceptive or misleading content on your behalf, such as doorway pages or 'throwaway' domains, your site could be removed entirely from Google's index. Ultimately, you are responsible for the actions of any companies you hire, so it's best to be sure you know exactly how they intend to 'help' you.”

Choose a reputable SEO firm

If you use an SEO firm to help with your website optimization, make sure you choose one that is reputable. Ask them about what SEO techniques they employ. Post questions and read online bulletin board comments about SEO firms. Be wary of ones who use roguish techniques to serve their own purposes. SEO companies who develop doorway web pages often include links to their own websites. Traffic may be redirected to websites other than your own, improving their ranking while decreasing yours.

SEO companies may want to use your domain server to host their own doorway pages, or even put “shadow domains” to other companies inside doorways that they create for you. Some will even guarantee ranking or offer to sell you keywords that work for your website. You may encounter an SEO company that offers you vague explanations or is altogether secretive about releasing their techniques and processes.

When you try to promote your website, always research the best SEO methods. You want to use effective methods that improve traffic to your site, and avoid techniques like doorways that may foil your potential customers and cause your website to be blacklisted from search engines. If you use an SEO firm to help your website, make sure they are ethical and do not use “tricks” to serve their own purposes.