Mail Checker for Proton Mail by beo
Check your Proton Mail inbox. Shows unread count, notifications, message preview, compose, reply, forward with attachments, calendar invites with RSVP, FIDO2 login, multi-account support, and end-to-end encryption.
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About this extension
Mail Checker for Proton Mail — access your encrypted inbox directly from the toolbar.
Website
https://apps.olausson.de/#mail-checker
Features:
* Multi-account support with per-account customization (labels, colors, reorder)
* Read, reply, forward, and compose emails with attachments
* Rich text editor with formatting toolbar
* End-to-end encryption for Proton-to-Proton messages
* OpenPGP attachment decryption — click to open in a new tab or download
* HTML, plain text, and raw email view modes
* Calendar invite detection with one-click RSVP (Yes/Maybe/No)
* Two-factor authentication: TOTP and FIDO2/WebAuthn security keys
* Mailbox-password / two-password account support
* Verification code detection with customizable regex patterns (premium)
* Desktop notifications with custom sound, volume, click actions, and preview-text toggle
* Custom toolbar badge color
* Do Not Disturb mode and message snooze (1h, 3h, tomorrow, next week)
* Three UI themes (Classic, Modern, Material) with Light/Dark/Auto color schemes
* Adjustable popup size, display density, and pop-out detachable window
* Custom CSS injection
* 28 European languages
* Settings sync across devices via Firefox account
* Settings export and import (JSON)
* Mailto: handler registration
* Credentials encrypted at rest (AES-256-GCM); SRP login (password never leaves your device)
Quick Actions: Mark read/unread, archive, delete, delete permanently, star, label, move to folder, snooze, report spam/phishing, view headers / message details — all from the popup. Drag-to-reorder and show/hide individual actions.
Compose & behavior options: Default compose / reply format (HTML or plain text), open compose in popup or Proton web, image-attachment mode (inline / attach / both), auto-mark-read on actions, auto-advance to next message, 12/24-hour time, sender display format, configurable polling interval, "Send & Archive" toggle, draft auto-save, contact autocomplete, spellcheck.
Privacy: No data collection. All API calls go directly to Proton Mail servers.
Website
https://apps.olausson.de/#mail-checker
Features:
* Multi-account support with per-account customization (labels, colors, reorder)
* Read, reply, forward, and compose emails with attachments
* Rich text editor with formatting toolbar
* End-to-end encryption for Proton-to-Proton messages
* OpenPGP attachment decryption — click to open in a new tab or download
* HTML, plain text, and raw email view modes
* Calendar invite detection with one-click RSVP (Yes/Maybe/No)
* Two-factor authentication: TOTP and FIDO2/WebAuthn security keys
* Mailbox-password / two-password account support
* Verification code detection with customizable regex patterns (premium)
* Desktop notifications with custom sound, volume, click actions, and preview-text toggle
* Custom toolbar badge color
* Do Not Disturb mode and message snooze (1h, 3h, tomorrow, next week)
* Three UI themes (Classic, Modern, Material) with Light/Dark/Auto color schemes
* Adjustable popup size, display density, and pop-out detachable window
* Custom CSS injection
* 28 European languages
* Settings sync across devices via Firefox account
* Settings export and import (JSON)
* Mailto: handler registration
* Credentials encrypted at rest (AES-256-GCM); SRP login (password never leaves your device)
Quick Actions: Mark read/unread, archive, delete, delete permanently, star, label, move to folder, snooze, report spam/phishing, view headers / message details — all from the popup. Drag-to-reorder and show/hide individual actions.
Compose & behavior options: Default compose / reply format (HTML or plain text), open compose in popup or Proton web, image-attachment mode (inline / attach / both), auto-mark-read on actions, auto-advance to next message, 12/24-hour time, sender display format, configurable polling interval, "Send & Archive" toggle, draft auto-save, contact autocomplete, spellcheck.
Privacy: No data collection. All API calls go directly to Proton Mail servers.
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Permissions and data
Required permissions:
- Input data to the clipboard
- Display notifications to you
- Access your data for sites in the proton.me domain
Optional permissions:
- Access your data for sites in the proton.me domain
Data collection:
- The developer says this extension doesn't require data collection.
More information
- Add-on Links
- Version
- 1.6.3
- Size
- 1.13 MB
- Last updated
- 6 hours ago (May 13, 2026)
- Related Categories
- License
- All Rights Reserved
- Privacy Policy
- Read the privacy policy for this add-on
- Version History
- Add to collection