[HOT-FIX] Duplicated email subject after enabling thread mode

[dab246]

Issue

Duplicated email subject after enabling thread mode

Reproduce

Steps to reproduce

Open any email while thread mode is disabled.
Go to Settings → Enable thread mode.
Go back to the previously opened email view.

reproduce.mov

Root cause

The issue occurs because the EmailView uses a GlobalKey, which prevents the widget from being disposed of when switching views. As a result, when the EmailView is rebuilt, it retains the previous object state within the class instead of creating a fresh instance, causing outdated or incorrect data (such as the old email subject) to be displayed.

Resolved

Screen.Recording.2025-10-17.at.12.48.09.PM.mov

[github-actions]

This PR has been deployed to https://linagora.github.io/tmail-flutter/4110.