Twitter joins the email address as universal-identifier club

Recently, I wrote on the topic of how Facebook, Linkedin, Plaxo and others are using e-mail addresses as “universal identifiers.” Simply put, I can upload a list of my e-mail contacts to be bounced against their database of registered users and they will tell me who among my contacts are already users of their service. This feature allows me to jump-start the creation of my personal network of users of the service. Some services like Linkedin and Plaxo allow me to export my list of contacts maintained within their “walls” back into my contact list. In other words, they are — in effect — allowing me to brick-by-brick, tear down their walls: They are allowing me the opportunity to export my social network with me when I start using another service. That’s the type of win-win relationship all sites that are “social” in nature should offer their users…and, in the future, no doubt, some form of “persistent network identifier” will be an expected feature of all sites that want me to share with them who my contacts are. (On September 7-8, there will be a Data Sharing Summit in Richmond, Calif., to explore such issues that may appear, on their surface, to be rather wonkish, but have important implications for “users” as well as developers of sites and services that depend on individuals forming social networks.)

Today, VC Fred Wilson (now an investor in Twitter) shares how Twitter is offering such a service whereby a Twitter user can bounce his or her GMail contact list up against the Twitter database to discover whether or not they have existing contacts on the service.

I really like this “import” feature as it provides a benefit to the user while adding to the growth potential of Twitter — we all benefit. However, there needs to be a corresponding “export” feature whereby I can export my Twitter contacts back in my direction.

That said — and, again, I’m a fan of such features — I don’t recall giving Twitter the permission to make my e-mail account public. Did I? If so, is there a way for me to opt out of allowing my e-mail address to be used as a universal identifier? Also, what if I have multiple email addresses and I only want one of them to used as an identifier, does Twitter have a way to let me toggle-off such addresses? (Linkedin is the benchmark for this feature.) For example, when I saw Fred’s post, I changed my address on Twitter to one that is the most publicly available of my email addresses (rexhammock[AT] While all such addresses make it into my in-box, some are rarely in people’s contact lists.

Also, while such “find folks from your contacts” features may work on sites that are explicitly “social networks,” are they appropriate for sites where “following” and “follower” is the nature of the relationships and networks? This is closely related to a topic I’m currently pondering — and writing about for a future post — the nature of online “friending.”

These are merely questions. No doubt, I’ll be bouncing my Gmail address book up against Twitter before the day is over. (Update: I did and it resulted in me adding 34 on my “following” list.) I’m a huge fan of Twitter and I like seeing them and others push the platform into whatever direction they believe can serve their interests — and the interest of their users — in new ways. Nevertheless, there are some “identity” and privacy issues inherent in such a feature that need to be aired.