To change email address you have to run Email Spy Control Panel.
If program is in visible mode you can click on Email Spy Control Panel shortcut
within Windows Start menu (as below):
Start -> Programs -> Email Spy -> Email Spy Control Panel
If Email Spy is in stealth mode you have to press program hotkey to run Control Panel (program default hotkey is Ctrl + Alt + Shift + E).

Click to email edit box to enter address where all outgoing SMTP-based emails
from monitored computer will be copied.
If you wish to have full control of all outgoing SMTP-based emails sent from monitored computer
you have to click to "Don't send emails to real recipient" checkbox.
Now all SMTP-based emails sent from monitored computer will be copied to your secret email address ONLY
(i.e. real recipients will not receive emails sent from monitored computer at all).

Then click Apply to save the setting and close Email Spy Control Panel.