1/ Reopen closed tabs in Safari — One of the most straightforward ways of reopening a tab in Safari is to click on the History button in the top-level menu bar, hover over Recently Closed then click on one of the displayed links. But you can also right-click (or hold down the Control key and normal-click) on the ‘Plus’ icon at the extreme right of the tab bar. A Recently Closed Tabs menu pops out and you can select your link from there.
2/ A key combo for last-closed tab — Mac owners have another advantage over (most) iPad owners in the form of a keyboard shortcuts. Shift-Command-T reopens the last opened tab —not so handy if you closed multiple tabs, but it can at least undo immediate mistakes.
3/ Closing tabs with swipes — Most Mac users know they can close a tab in Safari by either clicking on the tab’s small ‘x’ icon that appears on the left of a tab when your cursor is over it, or by using the keyboard shortcut Command-W (the universal Close Window command). But here’s a relatively unknown method for closing a Safari tab for multitouch gesture fans.
Note that the method described here doesn’t work in all situations. This tip involves a swipe gesture, so you’ll need to be using a MacBook’s built-in trackpad or a Magic Trackpad, but it also works on a Magic Mouse. The second caveat is that this only works for new tabs which launch automatically, for example, if you left-click on a website link that’s configured to open in a new page or a new browser window. This method won’t work for tabs that are launched manually by holding the Command key while you click or by using the right-click menu to Open in a New Tab.
If you click a link in Safari that opens in a new tab, two-finger-swipe back with two fingers to close the tab.
This is the same gesture you would normally use to go back to the previous page, and you would think it wouldn’t work in this case because there’s no “previous page” on a freshly opened browser tab. But, behold, if you’re working with a tab that launched automatically (as described in the caveats above), then this gesture closes the new tab and takes you back to your previous tab.
4/ Mailbox behaviours — To know how each of your email accounts (Gmail, iCloud, Comcast, Yahoo, etc) handles trash in the first place, look under Mail > Preferences. If you choose that and then pick Accounts from the following window, you’ll see a list of all of the email addresses you’ve set up in Mail on the left. Click one, choose the Mailbox Behaviors [sic] tab and you’ll see how often that particular account gets rid of its trash. You can set some, for example, to delete trash permanently when it’s a month old, which stops your Mailbox (which is on your ISP’s server) from filling up.
5/ Get rid of all Mail trash in one go — Click on the Mailbox menu and choose Erase Deleted Items. You can then erase the trash from all your accounts, or pick just a single one to clear out. But whichever way you go, you’ll then be rid of your old stuff. Make sure it’s not anything you actually need to keep, but if you run Time Machine backups this will all be safe anyway.
Extra tip — If you do have Time Machine, just running it does not make your Mail magically reappear. Here’s the trick: Boot Mail. Then boot Time Machine. If you do it this way, Time Machine becomes a dedicated backup server for just Mail, and all those deleted emails become available again.