Is there a way to know if a contact opened an email campaign that I sent?

Yes, you can be notified when a contact opens or clicks a link in an email campaign that you sent by choosing your notification preferences.
Follow these steps to set up your notification preferences:

1. Click the User Menu on the top right corner of the screen.
2. Click the Settings button.
3. Look for the My Preferences section.
4. Click Notification Preferences.
5. Go to the Email campaign alerts section.
6. Enable the desired checkboxes to receive your choice of notifications.