Hi All,
Adobe Send and Track doesn't save the email addresses used to share the files. You need to enter the emails manually every time you want to send the document link.
- If you are accessing the Send & Track service through desktop application Adobe Reader DC desktop application, then you will get the option to access the emails saved in your "Address Book" (as shown below). And this address book would be the email saved in the default email client of your computer.

- If you are accessing the service via web browser https://cloud.acrobat.com/send , then you wont get the option to access the address book. You need to enter the email addresses manually.
Note- Adobe Send & Track picks the default email account of your system. If you will change the default email to some other email then it will be changed for the Send & Track service too.
Hope this answers both the queries.
Regards,
Akanchha