Low Disk Space – System taking up 2.91 TB

Here is the EtreCheck report.

I noticed QuickLook is something listed a couple of times, and that is something that hasn't been working as well for a while.

I was having issues with the system running out of RAM and causing apps like InDesign and Illustrator to shut down, which is when I started investigating the disk space available (it had dropped to only 30 GB available).

The 2.78TB was all contained within the Drafts.mbox folder. This contained hundreds of folders, sub-folders, sub-sub-folders etc with many many duplicated files.

Here is a screenshot after nearly 24 hours, including reboot and running Disk Utility First Aid and trying to re-index Spotlight etc.

• About this Mac – space available is correct but the bar chart and Manage space are still incorrectly reporting Documents being 1.96TB.
• Disk Utility showing the correct free space (and no problems with the drive)
• Mail/V6 folder now correctly showing it's size at just over 100GB (this corrected itself around 2 hours after trashing the files)

Disk utility isn't showing much that is purgable.

I think Time Machine could be the culprit. I've had some issues with the Backup failing recently despite being allocated a 3TB external drive, and having Dropbox files excluded from backups. I'll take a look at the link you included and see if that helps.

Yes I've disabled Time Machine and disconnected the external drive it is allocated to.

Rebooted a few times, installed a software update, checked for Time Machine Local Snapshots.... this is still what I have available:

The Finder is showing the same amount of free space. I've unsynced some large Dropbox files to free up some space and left it for a couple of hours. When I came back the bar showing the space usage has changed to showing Documents and Mail being the main culprits. However it says the both have 1.9TB each which is larger than the total size of the disk.

I've just reindexed Spotlight for the whole Macintosh HD and am running EtreCheck now.

Thanks. I've just browsed to that folder in Finder and it certainly looks like the likely culprit:

My work email is hosted by Gmail and yes we do get some large attachments and lots of them in a working week. I have Mail.app as my preferred way of accessing my email. Other non-Mac based colleagues all tend to use Gmail.com.

Company policy is not to delete emails as we quite often go back to them months/years later.

The trash finally emptied (over 6 million items) and now Finder is showing 2.01TB available.

I've rebooted and followed the procedure to re-index Spotlight.

However Finder is still showing the V6 folder and contents to contain 2.78TB. And About My Mac is still showing the diagram of the disk to be full, despite reporting the correct free space figure.

Any ideas how to fix these last two niggles?

As Gmail is all IMAP – If I went offline, then deleted all the files in V6 and then went back online would that force Mail.app to redownload all the emails and attachments?

Wondering if I need to look at alternatives to using Mail.app and find a Gmail app like the ones I use on iOS... ?

I've done some more investigation, and there is/was a known issue with Mail.app saving draft emails (multiple copies of the same email and attachments) and not deleting them when they are sent.

I've found 3200 drafts on the Gmail server which I've deleted, and changed the Mail.app settings to only store drafts locally.

I've also trashed the Drafts folder shown above, this contained the 10 numbered folders, each of those contained 10 sub-folders, each of which contained 10 sub-folders etc.

Now emptying the trash... 622,000 items deleted and counting...

Thanks all for your help and suggestions, hopefully this is now resolved.