v1.13.0 - Post-quantum support (beta), and fewer permissions

• Beta support for Proton accounts that have post-quantum encryption enabled: they can now sign in and read their mail.
• The extension now asks for three fewer permissions. It no longer requests access to browser cookies, to network requests, or to the clipboard.
• Fixed "Open in Proton Mail" opening the wrong account if you had signed into the same account more than once in the browser.
• Fixed new encryption keys added to your account not being picked up until the browser was restarted.

Post-quantum support is marked beta because it could only be tested against keys generated locally, not against a live Proton account with the option enabled. Everything else works as before either way. Please report anything that looks wrong.

v1.12.10 - Bulk actions menu

• Fixed an issue where the top of the bulk actions menu was cut off, putting
  its first entries out of reach.

v1.12.9 - Confirmation prompts and draft safety

Settings

• Fixed an issue where confirmation prompts did nothing at all in Google Chrome.
• Confirmation prompts now appear next to the button you pressed, instead of
  somewhere off-screen.

Writing

• Fixed an issue where a reply could not be closed once you had typed in it.
• Fixed an issue where a recipient you were still typing was lost when the
  popup closed.
• Fixed an issue where a link could not be edited after adding it.
• A reply now opens at the top, ready to type above the quoted message.
• You are now told when a draft could not be saved, while there is still time
  to copy it.

Reading

• Fixed an issue where declining to discard a reply archived the message anyway.
• Fixed an issue where a keyboard shortcut could act on a message while a
  confirmation was still open.

v1.12.8 - Fixes from a full review of the extension

Sending

• Fixed an issue where a message could be permanently deleted if the connection
  dropped at the moment it was sent.
• Fixed an issue where a recipient you typed but did not confirm was left out of
  the message, without any warning.
• Messages that Proton temporarily refuses are now retried automatically, and
  the error you see if that fails no longer tells you to sign out.
• Fixed an issue where an embedded image could arrive broken when replying to or
  forwarding a message from some mail programs.
• Fixed an issue where replying to a calendar invitation failed if the event
  title contained an emoji or an accented character.

Writing

• Leaving a reply you have started now asks before discarding it, from every way
  of leaving it rather than just one.
• Fixed an issue where a long reply, or one quoting a large image, could fail to
  be saved as a draft.
• Fixed an issue where files chosen with the paperclip could be lost if the
  message you were replying to was no longer in the list.

Reading

• A quoted message can no longer borrow the extension's own styling to disguise
  itself as part of the interface.
• Fixed an issue where an image in a quoted message could still contact the
  sender's server before you chose to load remote content.

Also

• The "Image attachments" setting now reads "Attach as file" for everyone who
  had never deliberately changed it, so nothing changes unexpectedly.
• Messages that need reading now stay on screen long enough to read.
• The diagnostic log records more about a failed send, which makes a bug report
  usable. It still contains no message content or recipient addresses.

v1.12.7 - The image attachment setting now works

• The "Image attachments" setting in Settings now does what it says: an image
  you attach can be embedded in the message, attached as a file, or both. It
  previously attached as a file whichever option was selected.
• The default remains "Attach as file", so nothing changes unless you pick one
  of the other two.

v1.12.6 - Inline images that work outside Proton

Fixed

• Fixed an issue where an image pasted into a message did not appear for
  recipients outside Proton, such as Gmail and Outlook.
• Fixed an issue where an embedded image in a quoted message was lost when
  replying to it or forwarding it.
• Fixed an issue where an embedded image in a quote appeared broken while
  writing the reply.

New

• A mistyped recipient address is now marked while you type it, instead of the
  message failing at send time with a note about your connection.
• Leaving a reply you have started now asks before discarding it, as leaving a
  new message already did.
• Clearing the diagnostic log now confirms that it worked.

Also

• The "Discard draft?" question is now translated into all supported languages.
• Send failures record more detail in the diagnostic log, so a report about a
  failed send can be acted on.

v1.12.5 - Security fixes on the sending path

Includes everything from 1.12.4, which was never published.

Security

• Fixed an issue when sending password-protected messages to external,
  non-Proton accounts.
• Fixed an issue where a failed recipient key lookup could send a message
  without end-to-end encryption instead of stopping with an error.

Reading mail

• Images a message carries inside itself no longer need "Load external content".
• Attachments open in the browser only for file types that cannot carry active
  content; anything else downloads.
• Stricter cleaning of message HTML in the reading pane and in quoted replies.

Writing mail

• The hourglass button is now called "Encrypted/Expiring message", so the
  password protection for non-Proton recipients can be found.

Also in this release (from 1.12.4)

• Outgoing mail is now always signed with the address's main key when an address
  has more than one.
• Sharing a file through Proton Drive now records the same key it signs with.
• Sign-in blocked by post-quantum keys is now confirmed with Proton in the
  diagnostic log rather than guessed.
• The cache of senders' public keys no longer grows without limit.

v1.12.3 - Post-quantum keys are now detected, and a lot of missing translations

Please note: post-quantum encryption is NOT supported yet. What this release
does is recognise it and behave sensibly, instead of failing in a way that
looked like a wrong password.

Proton has been offering opt-in post-quantum protection since May 2026. An
account that opts in keeps its existing keys and gains a new post-quantum one,
which this extension cannot read. Until now the extension might pick that new
key, fail, and tell you your mailbox password was wrong. It was not, and
retyping it could never help.

What changes:

• A post-quantum key is now recognised as one the extension cannot read, and is
  not tried.
• The extension falls back to the other keys on the account. In most cases
  sign-in, reading and writing then continue to work as before.
• If an account has no key this version can read, you get a clear message
  saying the account uses post-quantum keys and that support is not there yet,
  instead of being sent back to the password field.

What still does not work: a message encrypted only to the post-quantum key
cannot be opened. Real post-quantum support will follow in a later release.

If you have an account with post-quantum protection switched on and sign-in
still fails, please get in touch. That feedback is genuinely useful, because
this behaviour has not yet been confirmed against a live post-quantum account.

Fixed: a large number of screens that were only ever shown in English.

Eighteen texts existed in English alone, so every other language quietly fell
back to it. The most visible was the whole unlock screen for accounts with a
separate mailbox password, which appeared in English no matter which language
you had chosen. Also affected were the trial banners, the subscription messages
and the option for hiding Pro-only buttons. French was additionally missing
seven texts in the compose window.

All of these are now translated in all 28 languages, using the same wording
Proton's own apps use where one exists. A check now runs with every build so a
text cannot go missing in a language again.

v1.12.2 - Embedded images now show up

Fixed: images embedded in a message, the kind Proton Mail for Android attaches
when you share a screenshot, did not appear at all. They were not drawn in the
message, and they were not listed as an attachment either, so there was no way
to see or save them. The message looked as though the picture had simply gone
missing.

Embedded images are now displayed in the message where the sender put them.
They are fetched from Proton and decrypted on your device, like any other
attachment. Nothing is requested from the sender, so opening a message still
cannot tell them anything, and the setting for blocking external images is
unaffected.

They also appear in the attachment area below the message, so you can open or
download the original file. That area now shows the total size followed by
what makes it up, for example "307.81 KB, 1 embedded image".

Also fixed: exporting a message as .eml put embedded images in the wrong place
in the file, so other mail programs could not connect them to the message body
and showed them as loose attachments, or not at all. Exported messages now
match what Proton Mail's own web export produces, and open correctly in
Thunderbird, Outlook and Apple Mail.

Translations for the new label were added in all 28 languages.

v1.12.0 — Quiet mail rules

NEW: Quiet mail rules (Pro). A new section in the extension settings, below Notifications, where you write rules that match incoming mail and mute it. Each rule can match on any combination of:
- Sender address (matches anywhere in the address: a whole address, a domain, or a fragment)
- Sender name — the name shown in the message list, which is often quite different from the address
- Recipient address (useful for muting mail sent to one alias)
- Subject (regular expression)
- Body (regular expression)

For the mail a rule matches you can switch off any combination of four things:
- the desktop notification
- counting it in the unread badge
- the notification sound
- showing it in the message list at all ("Hide from inbox")

Rules are given a name and collapse to one line each, so a longer list stays easy to read. A "Test" button tries the rule you are editing against the mail already loaded and tells you what it would catch — so you can check a pattern without waiting for a matching message to arrive. If a rule with several conditions matches nothing, the result breaks it down per condition, which shows at a glance which one is blocking.

Good to know:
- Rules only affect what this extension shows you. Nothing is sent anywhere, and your mail in Proton is never touched: nothing is marked read, moved or deleted.
- Editing a rule takes effect immediately, and applies to the mail already loaded — not only to new arrivals.
- Sender, recipient and subject arrive with the message list, but the body does not. So a rule with a Body pattern makes each new message be downloaded and decrypted locally to test it. That text is held in memory only, never written to disk, and only fetched while such a rule is enabled. Leave Body empty if you don't need it.
- "Exclude from unread count" and "Hide from inbox" apply to the messages the extension has loaded (see "Max emails per account"); a matching message older than that window still counts.
- Regular expressions use JavaScript (ECMAScript) syntax — the pattern only, without slashes or flags — and matching is always case-insensitive.

v1.11.3 — Sign-in fixes for the free plan

Fixed: free users could not sign in again after their session expired. An expired session leaves the account in place waiting for a new sign-in, but that re-login was counted as adding a second account, so the free plan's one-account limit refused it and showed "premium required". The single account the free plan includes became unusable after the first session expiry. Signing back in to an account you already have is no longer treated as adding one — and the account is recognised even if you sign in with your username or another of your addresses.

Changed: signing in to an account protected by two-factor authentication or a security key (FIDO2) is now part of the free plan. How you secure your Proton account is a property of that account, not of a subscription, so it should never have been a paid feature. TOTP codes and hardware keys now work on both plans.

v1.11.2 — Readable mail in dark mode

Fixed: some emails were nearly unreadable in dark mode — dark text on the dark reading background. Mail composed in web.de, Outlook and similar clients wraps pasted text in a small white highlight, and the extension mistook that highlight for the message's own page background, so it skipped the light-background fallback that keeps such mail readable. A background now only counts as the message's own when it actually covers the whole message. The same change fixes the opposite case, where a newsletter's real background sits deep inside nested tables and was previously missed.

New: a reading-background button in the message toolbar (next to the HTML / TEXT / RAW indicator). It cycles the background the message is displayed on through automatic, dark and light, with its own icon per state, for the rare mail the automatic choice still gets wrong. The choice applies to the messages you read until you close the popup.

Fixed: the quick actions above an open message were cut off at the window edge when the popup is narrow — at small widths only about half of them could be reached. The toolbar now wraps onto a second or third row so every action stays available.

v1.11.1 — Quick-action fix

Fixed:
- The "View headers" and "Message details" quick actions in the message list now open the message with the requested dialog shown immediately. Previously they only opened the message preview, and you had to click the same action a second time in the preview toolbar.

v1.11.0 — Share via Proton Drive

NEW: Share via Proton Drive (premium). A new button next to the attach (paperclip) button in the compose and reply/forward editors uploads the picked files to your Proton Drive instead of attaching them, and inserts one public share link per file into the email body. Files are end-to-end encrypted client-side using the same wire protocol as Proton's official Drive web client — nothing is uploaded anywhere except your own Proton Drive.

Per-link options (set in a small panel before picking files):
- Permission: Viewer or Editor
- Expiration: presets (1/7/15/30/60/90 days), no expiration, or a custom date (max 90 days)
- Optional extra link password (recipients type it; it is never part of the link)

New settings (Options -> Share via Proton Drive), included in settings export/import and Firefox Sync:
- Drive folder (default "mcpm-shared-files", created under "My files" if absent; "/" for subfolders)
- Default link expiration (default 30 days)
- Default link permission (default Viewer)

Great for files over Proton Mail's 25 MB attachment limit, and for keeping control of a file after sending: links can expire, require a password, and the file can be updated or unshared in Proton Drive at any time.

Also in this release:
- Editor toolbar order is now: Attach file, Share via Proton Drive, Expiring message.
- Upload robustness: the picker tab keeps the background service worker alive during file selection (Chrome MV3), malformed data can no longer stall an upload, failed uploads keep the picker open so errors stay visible, and a failed permission/password update no longer leaves an orphaned public link.

Privacy: unsent drafts are now encrypted at rest.

Compose and reply drafts — including the message text, attachments, and any
send options such as an "Encrypted Outside" password — are now AES-256-GCM
encrypted before they are saved, the same protection already used for your
credentials. Files handed over from the attachment picker are encrypted too,
and existing drafts are migrated automatically. The Pro licence key now syncs
across devices only while "Sync settings across devices" is enabled, and a
removed licence can no longer reappear from stale sync data.

Also fixed:
- Reply and forward drafts now keep their attachments when the popup closes.
- Toolbar icons that had turned invisible in 1.10.1 (schedule arrow, expiring-
message hourglass, and the clear button on the schedule/expiry chip) are back.
- The "Encrypted Outside" password field has a show/hide toggle.
- The attachment picker is now translated into all 28 languages and no longer
closes silently if saving the picked files fails.

Fixed: "Open in Proton Mail" now opens the right view for every account.

Proton's web app routes emails by conversation ID when conversation grouping
is enabled and by message ID when it is disabled — and stores that setting
separately for each client (web, Android, iOS). The extension now detects each
account's web-client setting and builds matching links, so clicking an email
opens it reliably instead of failing with "Conversation does not exist" /
"Message does not exist". In conversation view, links land on the exact
message, auto-expanded within its conversation.

Unread badge counts follow the same per-account setting, so the badge matches
what the Proton web sidebar shows.

Mail Checker for Proton Mail 1.10.1

Maintenance release. Internal hardening of the new Schedule send / Expiring messages composer UI — the controls are now built with safe DOM construction instead of HTML strings. No user-facing changes.

Mail Checker for Proton Mail 1.10.0

New — Schedule send & Expiring messages (Premium)

You can now schedule when a message is sent and set messages to expire, right from the extension's composer, replies, and forwards.

• Schedule send — write now, deliver later. Click the arrow next to Send and pick a preset (in the morning, tomorrow, Monday) or a custom date and time.

• Expiring messages — have a message automatically deleted from the recipient's inbox and your Sent folder at a time you choose (up to 28 days).

• Encrypted Outside — when an expiring message goes to a non-Proton address, protect it with a password. The recipient opens it securely through Proton's link and enters the password you set (you can add a hint).

These options are premium features. Note: scheduling a custom date/time and password-protected messages follow Proton's own rules (a custom schedule time requires a paid Proton plan; passwords must be at least 8 characters).

Mail Checker for Proton Mail 1.9.5

New
- Faster startup: the popup now opens at your configured size immediately, instead of briefly showing the default size while it loads.
- Optional email cache (Settings -> Data -> "Enable email cache", off by default): your last message list is stored locally and encrypted (AES-256-GCM; message details only — never message text), so your inbox shows instantly when you start your browser instead of a "Checking mail…" spinner. A new "Clear cache" button wipes it anytime.
- The refresh button now spins while the extension is checking mail in the background, so you can see when an update is in progress.

Fixes
- Cold start: the cached message list now appears instantly after a browser or extension restart, instead of a spinner that was waiting for encryption keys to unlock.
- Session reliability: fixed a rare, intermittent false "session expired" caused by two token refreshes firing within a fraction of a second of each other (a token-rotation race). The extension now recognises a just-completed refresh and skips the redundant one.
- Updated translations across all 28 languages.

Mail Checker for Proton Mail 1.9.4

Fixed
• Fewer "session expired" interruptions, especially on browsers that aggressively suspend background extensions (notably Opera). The extension could occasionally invalidate its own Proton login token by refreshing it from two background instances at the same time. Token refreshes are now serialized across the whole extension and always re-check the most recent token first, which prevents that conflict.

Mail Checker for Proton Mail 1.9.3

Fixed
• Account settings no longer close unexpectedly. Changing an account's monitored folders — or typing a login / 2FA / mailbox-password code — no longer bounces you back to the inbox mid-action.
• Newly monitored folders show their mail right away. After adding a folder to monitor, its existing messages now appear on the next Refresh instead of after a delay.

Improved
• More detailed opt-in diagnostics. With "Enable debug logging" turned on (Settings → Data), the exportable diagnostic log now captures the full console trace (background + popup), making issues easier to troubleshoot. Off by default; nothing leaves your browser.

Mail Checker for Proton Mail 1.9.1

Fixed
• The "!" account-attention indicator on the toolbar icon now appears immediately when an account's session expires, and stays visible until you sign in again — previously it could show up with a delay and flicker on and off.
• When a session has expired, the extension no longer keeps retrying the dead session in the background.

Mail Checker for Proton Mail 1.9.0

New
• Greatly improved reply & forward editor — Replies and forwards now start from the correct address, including the exact +alias (sub-address) the mail was sent to. Edit the To / Cc / Bcc lines directly with contact autocomplete, and reply with the original message quoted inline so you can answer in context.
• Export emails as .eml — Save any message as a standard .eml file, including its attachments. Use it from the open message, or enable it as a hover quick action (Settings → Quick actions; off by default). Available in the free version.

Fixed
• Accounts no longer get unexpectedly signed out — An account could lose its Proton session roughly once a day because the extension was renewing its login token far too often. It now renews on a sensible schedule, which keeps the session alive.
• Calendar invite responses now stick — Accepting / "maybe" / declining an invite now correctly updates your status, including invites sent to a +alias or coming from external organisers (Microsoft Teams, Google, Outlook). Your response shows in the attendee list instantly (no need to reopen the email) and is reflected in Proton Calendar.

Also
• The toolbar icon now shows a "!" when an account needs attention (e.g. it needs you to sign in again), alongside the unread count.
• New optional diagnostics log (Settings → Diagnostics) to help troubleshoot account/session problems.
• Security and stability hardening, plus translations for all new text across 28 languages.

• Fixed: emails you delete, archive, or mark as read no longer occasionally re-appear in the list after a background refresh, after opening and leaving a message, or when acting on several messages in quick succession.
• Internal reliability improvements. No new permissions, and no change to how your data is handled.

• Calendar invites: Microsoft/Outlook (Teams) meeting invites now show the event card with Accept / Maybe / Decline and the correct date and time — previously some were shown only as a plain attachment. Invites sent to a Proton alias address now highlight your current response and let you reply from the right address.
• New: optional sender logos beside each sender — verified brand logos (BIMI) loaded privately through Proton, plus an opt-in fallback to the sender's own favicon. Both are off by default; turn them on under Settings.
• Reliability and internal code-quality fixes. No new permissions, and no change to how your data is handled.