Let me preface this by saying that I’m not a dotMobi hater and actually disagree with my esteemed colleague Cindy Krum and others who are calling for (or declaring) the “death of the .mobi” at this year’s SES San Jose. On the contrary, there’s evidence to suggest that dotMobi is growing faster than most TLDs and the organization itself deserves credit for foregrounding a positive mobile user experience when so many consumers cite a poor user experience as a reason for avoiding the mobile Web. By contributing resources for mobile developers and mobile marketers and actively promoting mobility, as an organization they have done more than most to speed adoption of the mobile Web, and in turn the marketing to users of the mobile Web that we’ve all been hoping for. There are actually many reasons to acquire a dotMobi domain for your site (direct navigation and usability among them), but none of them, currently, involve SEO.

From an SEO standpoint, if you already own a dotcom domain, hosting your mobile site at the dotMobi might even hurt you, as doing so doesn’t’ take advantage of site factors like age of domain and link popularity that could help your site become more visible in search engines. As it is, there’s currently no evidence that dotMobi is a mobile search quality signal for the most popular mobile search engines or that dotMobi sites do better in search results. There is some evidence, however, that like any new domain in search results without the benefit of age and link popularity, they do worse.

For that reason I typically recommend both buying a dotMobi for your brand, and permanently redirecting it to the dotcom version of your site, hosted at m.domain.com or some easy to type alternative (e.g. domain.com/m).

Whether you choose to redirect the dotMobi to the dotcom or the dotcom to the dotMobi, redirect one of them for better visibility in search engines. Though it might be tempting, do not host a dotMobi site and a dotcom site with the same content. In SEO and mobile SEO this is duplicate content, and it won’t help your SEO efforts.

To illustrate, I’m going to use the new m-commerce site from Ralph Lauren at m.ralphlauren.com and polo.mobi. Ralph Lauren has been getting a lot of well-deserved press for their pioneering mobile commerce site and to salute their commitment to mobility I’m going to give them a link and a bit of free advice: redirect the dotMobi. There’s a lot wrong with this site in terms of SEO, but this is one of the biggest and most common.

Keep in mind, duplicate content in mobile search isn’t always bad currently. As we point out in the Resolution Media mobile SEO white paper, creating different mobile versions of your mobile content can actually help make it more visible. Look at the Google mobile search results for movie tickets for confirmation.

Google mobile search for “movie tickets”

MovieTickets.com has four of the six listings on the page, precisely because they created multiple mobile sites and hosted them at the .com domain. Had they blocked those with REP, as some consultants inexplicably suggested at SMX Local & Mobile, they would have had one of six listings on the SERP.

The difference between this and the Ralph Lauren site, however, is that the duplicate content for MovieTickets.com is all hosted at the dotcom TLD, while Ralph Lauren has duplicate content on different TLDs. As a result, Google mobile has all but made the dotMobi invisible even for RL brand terms, and you literally have to put in the keyword polo.mobi to find it in the mobile engine.

My advice to those looking to optimize their mobile site: don’t let Google decide which site is canonical and which should be suppressed. Whether you decide on dotMobi or dotcom as the TLD for your mobile site, pick one and permanently redirect the other. My recommendation is to permanently redirect the dotMobi to the dotcom, as it’s currently best for mobile SEO in the most popular mobile search engines; but the dotMobi is far from dead and should certainly be acquired. Just don’t host two sites at separate TLDs, or one of them will be suppressed. Better to consolidate your link popularity while giving mobile users a positive user experience, regardless of how they choose to access your site.