# Terms of Use

**Last Updated:** January 20, 2026

## Acceptance of Terms

By downloading, installing, or using Aerion ("the Application"), you agree to be bound by these Terms of Use ("Terms"). If you do not agree to these Terms, do not use the Application.

## Description of Service

Aerion is an open-source desktop email client. The official Aerion website and online documentation is hosted at [https://aerion.3df.io](https://aerion.3df.io). Aerion allows you to:

- Connect to email accounts via IMAP/SMTP
- Send and receive emails
- Manage email folders and organization
- Sync contacts from CardDAV, Google, and Microsoft services
- Use OAuth authentication for Gmail and Outlook

Aerion is a local application that runs on your computer. We do not provide any cloud services, email hosting, or server infrastructure.

## Open Source License

Aerion is licensed under the Apache License 2.0. You can:

- Use the software for any purpose
- Distribute copies of the software
- Modify the software and distribute your modifications
- Use the software commercially

Subject to the conditions of the Apache License 2.0, including preservation of copyright notices and disclaimers. The full license text is available in the LICENSE file included with the Application and at [https://github.com/hkdb/aerion](https://github.com/hkdb/aerion).

## User Responsibilities

You are responsible for:

1. **Account Security** - Maintaining the security of your email account credentials
2. **Device Security** - Securing the device on which Aerion is installed
3. **Legal Compliance** - Using the Application in compliance with applicable laws
4. **Email Provider Terms** - Complying with your email provider's terms of service
5. **Backup** - Maintaining backups of important data

## Acceptable Use

You agree not to use Aerion to:

- Send spam, malware, or phishing emails
- Violate any applicable laws or regulations
- Infringe on the rights of others
- Attempt to gain unauthorized access to email accounts or systems
- Engage in any activity that could damage or impair the Application

## Disclaimer of Warranties

**THE APPLICATION IS PROVIDED "AS IS" AND "AS AVAILABLE" WITHOUT WARRANTIES OF ANY KIND, EITHER EXPRESS OR IMPLIED.**

To the fullest extent permitted by law, we disclaim all warranties, including but not limited to:

- Implied warranties of merchantability
- Fitness for a particular purpose
- Non-infringement
- Accuracy or reliability of the Application
- That the Application will be uninterrupted, secure, or error-free

**Aerion is pre-release software currently in active development. Features may change, and bugs may exist. Use at your own risk.**

## Limitation of Liability

**TO THE MAXIMUM EXTENT PERMITTED BY LAW, IN NO EVENT SHALL THE DEVELOPERS, CONTRIBUTORS, OR SPONSORS OF AERION BE LIABLE FOR:**

- Any indirect, incidental, special, consequential, or punitive damages
- Loss of profits, data, use, goodwill, or other intangible losses
- Any damages arising from:
  - Your use or inability to use the Application
  - Any unauthorized access to or alteration of your data
  - Loss or corruption of emails or other data
  - Any third-party conduct or content
  - Any bugs, viruses, or other harmful code

**This limitation applies regardless of the theory of liability (contract, tort, or otherwise) and even if we have been advised of the possibility of such damages.**

## Indemnification

You agree to indemnify, defend, and hold harmless the developers, contributors, and sponsors of Aerion from any claims, damages, losses, liabilities, costs, and expenses (including reasonable attorneys' fees) arising from:

- Your use of the Application
- Your violation of these Terms
- Your violation of any rights of another party
- Your violation of any applicable laws

## Third-Party Services

Aerion integrates with third-party services including:

- Email providers (via IMAP/SMTP)
- Google APIs
- Microsoft APIs
- CardDAV servers

Your use of these services is subject to their respective terms of service and privacy policies. We are not responsible for the availability, accuracy, or practices of these third-party services.

## Modifications to the Application

As an open-source project, Aerion is continuously evolving. We may:

- Add, modify, or remove features at any time
- Release updates that change functionality
- Discontinue development

We have no obligation to maintain, support, or update the Application.

## Changes to These Terms

We may update these Terms from time to time. Changes will be reflected in the "Last Updated" date. Your continued use of the Application after changes constitutes acceptance of the new Terms.

## Severability

If any provision of these Terms is found to be unenforceable, the remaining provisions will continue in effect.

## Entire Agreement

These Terms constitute the entire agreement between you and the developers of Aerion regarding the use of the Application, superseding any prior agreements.

## Contact Us

If you have questions about these Terms of Use, please contact us at:

**Email:** aerion@3df.io

**GitHub Issues:** [https://github.com/hkdb/aerion/issues](https://github.com/hkdb/aerion/issues)
