I discovered 15GB of gmail data in Apple Mail. This huge multicoloured box turns out to be the Gmail ‘All Mail’ I could do this pretty confidently because my macbook air is my second machine, all my photo’s are only home computer if anything goes wrong.

While I was at it I went to my ‘Applications’ folder and deleted the old ‘iphoto’ app which took up 1.7GB. I just dragged this to the trash and saved 6.6GB. To find the file just right click on the box and select ‘reveal in finder’: Deleting my old iPhoto library released almost 7 G of space! El Capitan came with a new app called ‘Photos.’ The new Photos app imported my old iPhoto library, but it didn’t delete it! They are the same photos, the entire library has been duplicated. The large turquoise section to the left is the new ‘Photos’ library. Look at this screenshot from Disk Inventory X: The pink section surrounded by the yellow line is my old ‘iphoto’ library. I ran Disc Inventory X to see where the excess space was taken. To run well a mac hard disk needs at least 20% free. I just noticed after El Capitan that I lost a lot of space. Don’t forget to empty the trash once you are done.My MacBook Air is running a 120GB SSD drive so I don’t want my hard drive full of excess things I don’t need.Drag any attachment you do not wish to keep to the trash.To close the Quick Look preview click the space bar again.The item should be displayed in the Quick Look preview window.To Quick Look, an item, select the item and click the space bar.Because the attachments are likely to be known file types, you can use Quick Look to see the content of the file without opening it in an application. You should check inside each folder for attachments, as well as any individual files. You will likely find individual files within the folder, as well as folders with names containing a long string of numbers and letters.

Double-click the mail downloads match in the folder category and the folder will open in a Finder window.

Give Spotlight a little bit of time, then look for matches in the Folder category.

Spotlight will build a list of matches.

Enter ' mail downloads' without the quote marks in the Spotlight search field.

Open Spotlight by clicking on its icon in the Mac menu bar.

Clean up disc space on mac