Terms of service
emailz is a personal application with a single user, who is also its author. These terms exist because Google asks any application requesting account access to publish them.
Availability
The application is not offered to the public. There is no sign-up, no subscription, and no means by which a person other than its owner can connect an account to it. Nothing here constitutes an offer of a service.
Use
The application is used solely by its owner, against Google accounts belonging to him, to summarise and organise his own mail. It sends no email on anyone's behalf and permanently deletes nothing.
No warranty
The application is provided as-is, with no warranty of any kind. It is a personal project running on home hardware; it may be unavailable, may be changed at any time, and may be switched off permanently without notice.
Data
Handling of Google account data is described in the privacy policy, which is the substantive document of the two.