Users can now choose Automatic Temp Address, a genuinely Short Address (7-character randomized local part), or a Custom Address. They can also select an available domain reported by the configured mail infrastructure or leave it on Automatic.
I enforced the rules we established: creating a new address always adds another mailbox instead of replacing an existing one, existing mailboxes survive the update, and MaskMail never cosmetically shortens an email address. Complete real mailbox and sender addresses are allowed to wrap rather than being replaced with ….
I also changed the remaining dashboard navigation from “Install / uninstall” → “Updates”, synchronized the visible version to 0.6.6, and added regression checks for custom-address collisions, domain selection, existing-mailbox preservation, and narrow mobile layouts.

The main improvement is a formal storage schema/migration system, so future releases can change MaskMail's internal structure without treating existing user data as fresh/default data. Existing mailbox addresses, provider sessions, names, cached messages, read/Spam state, and rules are preserved during normal updates.
I also caught an important recovery edge case: if a user intentionally deleted their last mailbox, the older recovery snapshot could potentially restore it later. v0.6.5 now clears that stale recovery snapshot when the final mailbox is deliberately removed.
The QA plan now explicitly covers 1, 5, and 10 mailbox upgrades, provider outages during updates, intentional deletion, update/reload recovery, and 280–480px mobile dimensions with increased text scaling.

found and fixed an important regression: although the backend supported 10 mailboxes, both the popup and dashboard still disabled Add Inbox at 5. They now correctly allow all 10.
I also added:
Provider health memory so MaskMail remembers temporary infrastructure failures.
5-minute provider cooldown after failures instead of repeatedly hitting an unhealthy service.
Healthy infrastructure is preferred automatically.
Successful requests clear previous failure/cooldown state.
If every provider is temporarily unhealthy, MaskMail can still intelligently retry rather than leaving mailbox creation permanently stuck.
Manual Refresh now has proper busy/error handling and always re-enables the button.
Existing mailboxes remain bound to the infrastructure that originally created them.
Rechecked the narrow 280–320px mobile layouts, long email addresses, Idaho panel, reader sizing, and landscape constraints.
JavaScript syntax, manifest JSON, version synchronization, and ZIP integrity passed.

I also hardened several behaviors that could have caused subtle problems:
Spam messages no longer inflate the unread toolbar badge.
Spam/restore operations now verify the message actually belongs to the active mailbox.
Expired provider-side messages now have their stale read/spam state cleaned up during refresh.
Active mailbox read state is synchronized after background refresh.
Multi-mailbox switching and removal were rechecked.
Existing custom mailbox names, five-mailbox support, Spam folders, mobile UI, Cash App and Venmo support remain intact.
Firefox's manifest configuration is appropriate: data_collection_permissions arrived on desktop in Firefox 140, while the corresponding built-in Android support arrived in Firefox 142, matching the current desktop/Android minimums.