Sites like Twitter and Foursquare know that the number of registered users is not nearly as important as the number of active users. So, it's important for these companies to communicate with users to ensure they stay relevant.
Twitter now has 200 million users, but how many are active? One year ago, RJ Metrics reported that only 20% of Twitter's users were active (then 15 million out of 75 million users). Twitter sends emails to users infrequently, so it's surprising that this one was rather uninspiring. First, it's a "Happy New Year" message that was sent on February 1 - did this email spend three weeks getting internal approvals?
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