There is a way to send an email message to only a portion of a list.  You can use a suppression list to block certain emails  For example if you have 20 email addresses you don’t want to email, you can add these to a suppression list file and select suppression list this during campaign setup. This will send to everyone on the list except anyone listed on the suppression file. Basically what happens is our system cross references your mailing list with the suppression list and doesn't mail those email addresses on the suppression list.
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This is for suppression lists that are encrypted in md5 hash. MD5 hash selection will decrypt an encrypted suppression list and add only the email addresses that are on your list to the suppression file. MD5 hash is an encryption method. 

FTP upload is not available at the moment but you can use zip archived file and the max size limit is 410MB.