Show preview pane
· This shows or hides the Preview Pane in the mail view.
Mark previewed messages read
· Select the delay to mark new messages as “read” when opening them in the preview pane.
Request for receipts
· This option controls the behavior when you open a message for which the sender requested a read receipt.
Expand message threads
· When listing messages in threads, this option controls how conversation groups are expanded in the list.
Rows per page
· The messages list displays this number of messages at a time (aka a “page”). Increasing this number may result in longer loading times when opening a mailbox folder.
Check all folders for new messages
· By default, only the Inbox is checked for new messages periodically. If you have server-side filters installed that will move incoming messages to other folders, you should check this option.