You can ask the sender for the decryption passphrase.
Drop-Off Summary
This is a terms and conditions waiver that recipients must agree to.
To disable it, see the settings showRecipientsWaiverCheckbox and defaultRecipientsWaiver in /opt/zendto/config/preferences.php.
It can be long and may contain HTML tags.
To change this text:
look for this text in the /opt/zendto/config/locale/*_*/LC_MESSAGES/zendto.po text files
put your own text in msgstr "..." line(s) immediately following it
run /opt/zendto/bin/makelanguages as root
restart Apache (to ensure it really picks up the new text).