If you go into your profile page, the little person icon upper left, and click on "change your site preferences". This will take you to the page where you can select to receive email notices for tree mail, it is the third row down.
There are many different functions...one of my favorites is the "Custom Menubar". When you click "manage your custom menubar" it takes you to a page for adding web links to other sites or pages. Type in what you want to call your tab, copy/paste the web address and click the green bar to save your changes. The new tab will be over on the left under the NGA tabs. Makes it easy to get to the AHS website, AHS Database, the Lily Auction, ...whatever sites or pages you want to add.