re :once clicking at the specified mail without opening the email itself.

There is no such thing as a preview. A single click on email in list opens the email in the 'Message Pane' assuming the Message Pane is enabled.

A double click on email in list will open email in either a new tab or window depending upon what you have set up in Options.

In both cases the email is opened. Many people like to use the Message Pane as it is a quick method of reading emails, but opening in a new tab can be useful if the email is more lengthy and you prefer a bit more space to read more easily without so much scrolling.

The only other option to read contents of an email without opening would be to look at the source.

• Close the 'Message Pane'.
• Single click to highlight email - will not open email as 'Message Pane is switched off.

• Via 'Menu Bar' toolbar: 'View' > 'Message Source'

OR

• Via 'Mail Toolbar' toolbar: 'Menu icon (3 lines)' > 'View' > 'Message Source'

OR

• use 'Ctrl'+'U' keys

How to enable/disable the Message Pane:

• Via 'Menu Bar' toolbar: 'View' > 'Layout' > select 'Message Pane'

OR

• Via 'Mail Toolbar' toolbar: 'Menu icon (3 lines)' > 'Options' > 'Layout' > select 'Message Pane'

OR

• you can easily toggle the view on and off using the F8 key

You can choose to have the Message Pane open immediately below the list of emails ('Classic') or you can use the entire lower section which limits the height of the Folder Pane ('Wide') or you can have the Message Pane appear on the right side ('Vertical'). If you do not have a wide screen then you will find opening on the right not so easy to read the list of emails.

How to choose 'Vertical' position of Message Pane:

• Via 'Menu Bar' toolbar: 'View' > 'Layout' > select 'Vertical'

OR

• Via 'Mail Toolbar' toolbar: 'Menu icon (3 lines)' > 'Options' > 'Layout' > select'Vertical'

If you select more than one message in the Threads Pane (message list), the first few lines of each message is shown in the Message Pane, as e.g. '3 Conversations', if you selected 3 messages.