Last updated: March 14, 2026
These Terms of Service ("Terms") govern your use of the Lightspeed email client ("Service") provided by Lightspeed ("we", "our", "us"). By using Lightspeed, you agree to these Terms.
By downloading, installing, or using Lightspeed, you agree to be bound by these Terms. If you do not agree to these Terms, do not use the Service.
Lightspeed is a desktop and mobile email client for Microsoft 365. It provides a keyboard-first interface for managing your email, calendar, and contacts. Optional AI features are available through integration with Google's Gemini API.
You must have a valid Microsoft 365 account to use Lightspeed. You are responsible for maintaining the security of your Microsoft account credentials. Lightspeed authenticates through Microsoft's official OAuth 2.0 flow and does not store your password.
You agree not to:
AI-powered features (auto-drafts, smart replies, summarization, Write with AI) require you to provide your own Google Gemini API key. You are responsible for any costs associated with your API usage. AI-generated content is provided as suggestions and should be reviewed before sending.
Offline voice-to-text features use Whisper AI models downloaded to your device. You are responsible for downloading and managing these models. Voice processing occurs entirely on your device.
Lightspeed and its original content, features, and functionality are owned by Lightspeed and are protected by international copyright, trademark, and other intellectual property laws. Your email content remains your property.
Your use of Lightspeed is also governed by our Privacy Policy, which describes how we handle your data.
Lightspeed is provided "as is" and "as available" without warranties of any kind, either express or implied. We do not warrant that the Service will be uninterrupted, error-free, or secure. We are not responsible for any data loss resulting from the use of the Service.
To the maximum extent permitted by law, Lightspeed shall not be liable for any indirect, incidental, special, consequential, or punitive damages, including loss of profits, data, or goodwill, arising from your use of or inability to use the Service.
We reserve the right to modify, suspend, or discontinue any part of the Service at any time without prior notice. We shall not be liable to you or any third party for any modification, suspension, or discontinuation.
We may revise these Terms from time to time. The most current version will always be available on this page. By continuing to use Lightspeed after revisions become effective, you agree to be bound by the revised Terms.
These Terms shall be governed by and construed in accordance with the laws of the United States, without regard to conflict of law provisions.
If you have questions about these Terms, please contact us at legal@lightspeed.email.