FOLD Documentation
Early access
Security and privacy

Network connections

Every server FOLD talks to, when, and why.

This is the complete list of connections FOLD makes on its own or on your request. There is no FOLD server in the path of your mail.

Your mail servers

FOLD connects to the IMAP and SMTP servers of your accounts, always encrypted:

  • TLS from the first byte, or STARTTLS. Unencrypted connections are refused, even if you select None as the security setting.
  • If STARTTLS fails, or the server sends data before encryption is in place, FOLD disconnects instead of continuing unencrypted.
  • The server certificate must be valid for the host name. There is no way to accept an invalid certificate.
  • The TLS version is negotiated by the operating system.

DNS

FOLD uses the resolver your device is configured with:

  • When you add an account: the SRV records of your domain (_imaps._tcp, _submission._tcp and related).
  • When FOLD downloads a message: the DKIM keys of the signing domains; for brand logos also the sender’s DMARC and BIMI records.

Account setup

FOLD asks your own domain for its autoconfig file, at autoconfig.<domain> and <domain>/.well-known/autoconfig. The request contains the domain, not your address. Mozilla’s central provider database is not queried.

Sign-in with Google

For Google accounts, the sign-in runs in the system’s web sign-in sheet at accounts.google.com. FOLD fetches and renews its tokens at oauth2.googleapis.com. Sign-in with Microsoft is prepared but not available yet.

  • Images in HTML mail: loaded from the sender’s servers only after you choose Load images.
  • Links: opened in your browser after you confirm them.
  • S/MIME revocation check: if you turn it on, FOLD asks the certificate authority’s OCSP or CRL server when you open signed mail.
  • Brand logos: the sender’s mark certificate, fetched from the address in its BIMI record, only after DMARC passed with an enforcing policy.
  • iCloud: the private CloudKit database of your Apple Account for device sync, and iCloud Keychain for password sync. Both are off until you turn them on. One exception: on a Mac without any accounts, FOLD reads your iCloud data once, read-only, to offer restoring accounts from another device. Nothing is written and sync stays off.
  • Unsubscribe: sends an email through your own server, or opens the sender’s web page in your browser. FOLD never sends an automatic one-click request.

Updates

The Mac version downloaded directly from foldmail.app checks for updates shortly after launch and once a day by fetching one static file, the signed update feed on Datargo’s download server. The request carries no user or device identifier. You can turn automatic checks off under Settings > General. The App Store and TestFlight versions contain no updater.

What FOLD never contacts

No analytics or crash-reporting services, no key servers, no link-checking services, no favicon or avatar services. FOLD does not send read receipts.