Privacy

Lambda Mail is a Mac app that connects your Mac straight to your Gmail account. We built it so that we never see your mail. This page says what the app does with your data, in plain words.

What the app accesses

Lambda Mail connects to Gmail over IMAP (imap.gmail.com) and SMTP (smtp.gmail.com), always encrypted with TLS. It uses that access only to show, search, send and organize your mail on your Mac.

Where your data lives

Only on your Mac. In its own sandbox folder, the app keeps a list of the messages in your mailboxes: for each one the sender, the recipients, the subject, the date, its labels, whether it is read or starred, and Gmail's message IDs. The list comes straight from Gmail and stays in step with it, so a message you delete in Gmail leaves the list at the next sync.

The text and attachments of a message are downloaded when you open it, along with the newest few messages in each mailbox. They are kept up to the size you choose in Settings › Accounts: 1 GB (the default), 5 GB or no limit.

The app also keeps your signatures, a list of addresses it has seen (for autocomplete) and your theme choices. Your sign-in is stored in the macOS Keychain.

Deleting your data

To remove an account, click Remove next to it in Settings › Accounts. Removing the account deletes everything the app stored for it: its sign-in in the Keychain, its message list and its downloaded messages. Your mail stays in Gmail.

To free up space and keep the account, choose Clear Cache in Settings › Accounts. It deletes the downloaded messages and attachments. To delete the message list as well, remove the account.

Deleting the app and its data removes everything else it stored: the addresses it has seen, your themes and your signatures.

What we receive

Nothing. Lambda Mail has no analytics and no tracking, and it has no servers of ours: your mail goes from Google to your Mac and nowhere else. We don't run any crash reporting of our own. If you choose to share crash reports with developers in macOS, Apple handles them. The beta adds one thing, from Apple and not from the app: if you join the beta through Apple's TestFlight, Apple shares with us what TestFlight collects for testers (the name and email you use for TestFlight, install and session information, crash logs, and any feedback you choose to send).

Pictures inside a message load automatically, so the sender's server can see that the message was opened. In Spam they stay blocked until you choose Load Images. Links open in your browser. If you choose Send Feedback, the app writes a normal email to us, and it is sent only when you send it.

Signing in with an app password

This is how the beta signs in today. You create an app password in your Google account and enter it in Lambda Mail, which stores it in the Keychain on your Mac. To revoke it, delete the app password on Google's app passwords page.

Signing in with Google

This section applies once Sign in with Google is available in Lambda Mail. It is planned and is not in the beta yet.

Lambda Mail will ask for the Gmail scope https://mail.google.com/, which lets the app read, send and organize mail over IMAP and SMTP. It uses that access only to show and manage your mail on your Mac. Access tokens stay in the Keychain on your Mac. We don't use your Google data for advertising, we don't sell it, and no person at Lambda Mail reads your mail.

Lambda Mail's use and transfer of information received from Google APIs to any other app will adhere to the Google API Services User Data Policy, including the Limited Use requirements.

You can revoke access at any time at myaccount.google.com/permissions.

This website

This website has no cookies and no analytics, and it loads nothing from other sites. If you join the beta, the email address you enter goes to Netlify, which hosts this site. We use it only to email you about Lambda Mail, starting with your beta invite, and we delete it when you ask. Like any form submission, the sign-up also gives Netlify the technical details your browser sends (your IP address, your browser and the page you came from), and Netlify checks submissions for spam with an outside service, Akismet.

Contact

Questions or a deletion request: mizikq@gmail.com.

Last updated: October 28, 2026