Paired t-tests are a form of blocking, and have greater power than unpaired tests when the paired units are similar with respect to noise factors that are independent of membership in the two groups being compared.
The service, by the way, is called AOL My eAddress. AOL says it supports .com or .net domains, up to 100 e-mail identities per domain, 2 GB of storage, spam filtering, and open mail clients such as Outlook and Thunderbird through the IMAP protocol.
Now AOL is trying to control the music download business with a new service called MusicNet@AOL. It's bad enough that AOL censors content and keeps track of what you see, now AOL wants to keep track of what you hear.