Hold the Ctrl key when selecting messages in the three-panel interface. To select all messages on the page, use the Ctrl + A keyboard shortcut.
Messages containing attachments are marked with. To view a list of files attached to a specific message, simply left-click the icon.
If you have frequent correspondence, enable the Group by theme option (above the list of messages, to the right). Your messages will be grouped into conversation threads. To expand or collapse a list of messages in a thread, click the subject of the message.
Each conversation displays all messages with the same subject, even if some of them are stored in other folders.
You can also move within a message thread by using the message page.
To view messages for a certain month or year, you can use the Messages by month toggle (below the list of messages, to the right).
You can only filter messages by month or by year within the current folder. If you do not see any messages for the specified period, make sure you have opened the right folder.
If none of the folders contain a message for the specified period, then the message does not exist in your mailbox. For details on why this issue might happen and how to resolve it, see Messages disappear from my mailbox.