Is any part of the SendNow process encrypted? Is the file that is being sent or the e-mail itself?
The communication between any given endpoints including browser and adobe is encrypted by virtue of using HTTPS. However, the file content stored on Adobe servers is not and neither is the email.
Note that with SendNow, the file is not sent with the email to the recipient. S/he gets a link from which the file is downloaded.
Hope this helps.