You can make a smart campaign, in which you can add the smart list for all 100% (can be the similar way you defined a smart list in the email program), and then add the filter "Not was sent Email" to send your desired email. You can clone your email and edit it's subject, and send the cloned (subject changed) email for the rest 90%
(Make sure that you Use ALL filters in the smart list)
Hope this hepls!