Well respected SEO, Scottie Claiborne, wrote a guest article for Jill Whalen's popular newsletter named Switching to a New Domain Without Losing Your Google Rankings. In her article, Scottie recommends using a 302 redirect temporarily, so that Google keeps your current rankings in place. Here is her direct advice:
By using a 302 "temporarily moved" response instead of a 301, the original URL will remain in Google's index, and maintain its position as if the page were still there. However, visitors who click on the link will be brought to your new URL, exactly where you want them to be. It's the best of both worlds -- you retain your rankings during that interim aging period, but visitors are redirected to the updated and correct domain.
Once the 302-redirect is in place, it's imperative to start a linking campaign for the new site. You'll need links pointing to it in order for it to be ready to rank highly when it's released from the aging filter. When you notice the new domain starting to show up in the rankings (anywhere from 6-12 months, typically) then it's time to contact your previous linking partners to update their links from the old domain to the new one.
Once the new domain has properly aged, go back and change the 302-temporary redirect to a 301-permanent redirect.
I have heard that this used to work about a year ago. But I honestly would never recommend this action.
It is an old article, and is dated as such, so be careful with old articles. Things that may have worked in the past, may kill you in the future.
A recent High Rankings thread shows one member giving this method a try. He claimed it bombed badly;
As per Scotty's advice, I set up a 302 redirect exactly as described and all went well until about a week ago. Google saw fit to remove all of the pages that were 302'd from the search results. The pages are still indexed, but they aren't even on page 10,000 of results that we used to rank #1 for.
So I figured I do some research as well as ask Google for some information on what to do in this specific situation.
(1) http://books.google.com/webmasters/3.html number 2 says:
2. I migrated my website to a new URL.
If you've changed your URL, or plan to, and would like Google to display your new URL, please keep in mind that we can't manually change your listed address in our search results. That said, there are steps you can take to make sure your transition is smooth.
If your old URLs redirect to your new site using HTTP 301 (permanent) redirects, our crawler will discover the new URLs. For more information about 301 HTTP redirects, please see http://www.ietf.org/rfc/rfc2616.txt.
Google listings are based in part on our ability to find you from links on other sites. To preserve your rank and help our crawler find your new URL, you'll want to inform others who link to you of your change of address. To find a sampling of sites that link to yours, perform a link search by entering "link:[your full URL]" into the Google search box. To find more pages that mention your URL, perform a Google search on your URL and select the "Find web pages that contain the term" link. Also, don't forget to change any entries you may have in directories such as Yahoo! or the Open Directory Project.
Finally, you may submit a list of your new URLs through the Google Sitemaps (Beta) program. Google Sitemaps uses webmaster-generated Sitemap files to learn about your webpages and to direct our crawlers to new and updated content.
Sometimes during site transitions, we'll fail to find a site at its new address. Just be sure that others are linking to you, and we should discover your new site.
(2) A post by Vanessa Fox named More about changing domain names:
Recently, someone asked me about moving from one domain to another. He had read that Google recommends using a 301 redirect to let Googlebot know about the move, but he wasn't sure if he should do that. He wondered if Googlebot would follow the 301 to the new site, see that it contained the same content as the pages already indexed from the old site, and think it was duplicate content (and therefore not index it). He wondered if a 302 redirect would be a better option.
I told him that a 301 redirect was exactly what he should do. A 302 redirect tells Googlebot that the move is temporary and that Google should continue to index the old domain. A 301 redirect tells Googlebot that the move is permanent and that Google should start indexing the new domain instead. Googlebot won't see the new site as duplicate content, but as moved content. And that's exactly what someone who is changing domains wants.
So 301 is recommended.
Other advice given to me by Google based on my recent request is to read the following blog posts:
- Setting the preferred domain
- Changing domains
- My URL changed, so how can I get Google to index my new site?
- SEO advice: url canonicalization
- SEO advice: discussing 302 redirects
- Moving to a new web host
So please be cautious when moving domain names. 301 is the safest best, even though it may take several months to get right.
I want to thank Ben for his help here, he may come in later and add his thoughts...
Forum discussion at High Rankings.