Where Does the Proton Mail Desktop App Store Local Data?
Proton Mail desktop app local data on Windows and macOS, and why mail itself stays encrypted server-side.
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The Proton Mail desktop app caches encrypted mailbox data locally for offline access while the authoritative copy stays on Proton servers. Signing in on a new machine re-downloads everything, so local folders are cache rather than archive.
Exact folder names follow Electron conventions and can shift between releases. The in-app Clear application data button is the supported reset path.
Where Proton Mail stores this, by platform
%APPDATA%\Proton Mail
Reported Electron user-data location for cache, session and offline mailbox state. Folder naming may vary by release, so verify on your install. Mail itself re-syncs from your account, so clearing this only signs you out. Prefer the in-app Clear application data option over manual deletion.
~/Library/Application Support/Proton Mail
Same cache and session role as Windows. The macOS build also ships an uninstaller that removes all traces. Reach the folder through Finder Go > Go to Folder.
Frequently asked questions
Will reinstalling Proton Mail desktop delete my emails?
No. Mail lives encrypted on Proton servers and returns on sign-in. Local folders hold only cache and offline copies.
How do I use Proton Mail with Thunderbird or Outlook?
Through Proton Mail Bridge, a separate local service with its own data directory, available on paid plans. The desktop app itself does not expose IMAP.
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