feat: mail display mode

Signed-off-by: SebastianKrupinski <krupinskis05@gmail.com>

admin_manual/groupware/mail.rst

@@ -86,6 +86,18 @@ Mailbox Share
 -------------
 Users can share mailboxes with each other. So far, there is no UI for users to change the ACL in the Mail app, but if you want to use it, you need to enable it on the IMAP sever and configure the shares there.
 
+.. _mail_ui_defaults:
+
+User Interface Preference Defaults
+----------------------------------
+
+.. versionadded:: 5.2
+
+The Mail app allows administrators to set default user interface preferences for all users, these preferences can be changed by the user afterwards. This can be useful to ensure a consistent experience across the application.
+
+.. figure:: images/settings_mail-ui-defaults.png
+   :alt: User Interface Preference Defaults
+
 .. _mail_llm_processing:
 
 LLM Processing

user_manual/groupware/mail.rst

@@ -19,6 +19,22 @@ Switch layout
 
 .. figure:: images/mail_layout.png
 
+Message Display / Operation Mode
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. versionadded:: 5.2
+
+Mail has the ability to switch between two different message view and operation modes: *Threaded* and *Singleton*.
+
+In *Threaded* mode, messages are grouped by conversation. In the mailbox message list, related messages are stacked so only the most recent message is shown, and all relates messages are shown in message display panel after the stacked message is selected. This is useful for following discussions and understanding the context of replies. In this mode, message operation like move and delete apply to the entire thread, meaning that when you move or delete a thread, all messages within that thread are affected.
+
+In *Singleton* mode, messages are displayed individually, in both the mailbox message list and message display panel and operation like move and delete apply to only the selected message. This mode is useful when you want to manage messages separately without affecting the entire conversation.
+
+1. Visit mail settings
+2. Choose between *Threaded*, *Singleton*
+
+.. figure:: images/mail_display-mode.png
+
 Add a new mail account
 ~~~~~~~~~~~~~~~~~~~~~~~