If you like to browse without the Hotlist and you use M2, you'll see that you actually need the Hotlist with the mail client. Change the following line in your standard_toolbar.ini under [Browser Toolbar]: Button9, "Mail"=Read mail into: Button9, "Mail"=Read mail & View hotlist, 7 & Focus panel, "Mail"
This way pressing the mail button in your main toolbar will not only show the Unread folder, but also the Hotlist.