Google can review or read all user communications, including private messages

The service can delete your account without prior notice and without a reason . At any time, your account can be terminated without explanation and without warning by the service.

The Agreement explains they will disclose personal data about you if it is reasonably necessary to comply with applicable law and government requests.

The service can read your private emails . The Service is able to access, scan, review or read all user communications, including private messages, which may contain personal or sensitive data.

Per the service's terms, users may not express negative opinions about them . Criticising, questioning, making objections or complaints about the Service, its staff or anything related to it is prohibited and constitutes a breach of the Terms.

Your data may be processed and stored anywhere in the world . Your data is stored all over the world, including in countries where data protection rules may differ from the ones of the service's jurisdiction or those of your country jurisdiction.

You are tracked via device fingerprinting . Tracking technologies (such as web beacons, tracking pixels...) are employed on users and/or the service assigns a unique ID to a browser or device to track its behaviour.

Terms may be changed any time at their discretion, without notice to you . The Agreements can be updated at any time, including in a way that negatively affects user rights, without notifying before or after the changes.

Instead of asking directly, this Service will assume your consent merely from your usage. . The Service infers your acceptance from your continued usage, instead of prompting you to read the new Terms and asking for direct consent. This doesn’t apply to services that have no way to seek consent from users through their contact details or an account.

Per the service's terms, users may not express negative opinions about them . Criticising, questioning, making objections or complaints about the Service, its staff or anything related to it is prohibited and constitutes a breach of the Terms.

Not even when "Don't be evil" was still their motto did Google not only have the ability to read all communication that was routed through them, they actively used those messages to develop their offerings.

The only system or organization you should trust to not read your messages is one that never gets to see your messages unencrypted. In all other cases, assume the organizations involved in relaying your message can read them, and will do so if they (or any of their employees, or contractors, who happen to have access) think of a reason.