How to reduce SYSTEMDATA size by disabling Connection Activity Log in Email on Mac?

Why is SYSTEMDATA on my MAC OS 80% of my 256 GB of HDD space?


I have been search for years. I have followed all APPLE Community

findings and installed and run disk clean up tools and nothing changes.


Second, deleting caches, logs, downloads etc… would give one to two gigs back but SystemData would just suck it up. I can not tell you how many times I have done that :(.


Looking at a file level I found the single file that was the enormous. Tracing it back I would it was a email Connection Doctor log.  Woo!


So to clean this up it’s simple. Open Email, got Window them Connection Doctor.  If your Connection Activity Log is enabled then disable it.


Select Show Logs, drag them to the TRASH ( I love saying that! ), then empty the trash.  Once done, restart the MAC and SHAZAM the issue is resolved.


Have a better day!


[Re-Titled by Moderator]

Original Title: Cleaning SYSTEMDATA

MacBook Air (M3, 2024)

Posted on Sep 15, 2026 5:17 AM

Reply
2 replies

Oct 19, 2026 10:43 AM in response to SystemDataMan

SystemDataMan wrote:
So to clean this up it’s simple. Open Email, got Window them Connection Doctor.  If your Connection Activity Log is enabled then disable it.
Select Show Logs, drag them to the TRASH ( I love saying that! ), then empty the trash.  Once done, restart the MAC and SHAZAM the issue is resolved.
Have a better day!
[Re-Titled by Moderator]
Original Title: Cleaning SYSTEMDATA



Good computing SystemDataMan !

It can be a contributing issue to "SYSTEMDATA" but not necessarily the only cause.

ref: Free up storage space on Mac - Apple Support


Have not heard reference to this issue in quite sometime— but it is a known issue.

These mail logs are not turned on by default..


I have seen anywhere from 12 GB to 700 GB of logs built up here.

ref: Mail IMAP txt Log too big, Catalina 10.15… - Apple Community

You would be safe to delete all those logs/ .txt files.


Mail>Window>Connection Doctor




Oct 19, 2026 3:54 PM in response to SystemDataMan

You should aim to have 15-20% of your total internal storage as free space (~30-40 GB as an absolute minimum). If you do not have enough free space on your Mac’s internal storage, then here are some steps to take to safely free up space:

Free up storage space on Mac - Apple Support

Optimize storage space on your Mac - Apple Support

How to free up ‘System Data’ and other st… - Apple Community

 

"System Data" comprises your data, but they are typically hidden files that Spotlight cannot assign to a specific category like Documents or Applications. Examples include Outlook attachments, iOS updates, Cloud storage caches, etc. Starting with macOS 27 Golden Gate, System Data also includes what macOS used to call ‘purgeable’ storage – system caches, Time Machine snapshots and some other data, though the user had no control over the purging. Trying to manually clean out hidden files in System Data is likely to cause more problems than it solves, macOS hides those files for a good reason. Follow the steps in the linked articles above. 


You can check the amount of free space you have on your Mac in a variety of ways:

  • Select your internal drive then click File menu > Get Info, check Available space
  • Go to System Settings > General > Storage, check the graphical display at the top of the settings pane
  • In Disk Utility (in Applications > Utilities), by selecting the main container disk below the drive itself (you may need to select View menu > Show all devices to see it)
  • In the System Report – hold the Option key and click the Apple menu > System Information (the top menu item), look for the name of your internal drive (Macintosh HD, unless you have renamed it as I did)


On Tahoe, use one of the last two options, the first two show 'available' space which is not the same as free.



More detail on this change in this User Tip:

System Data and Free Space Changes in Gol… - Apple Community

 

The best advice is to just ignore the System Data category. ‘System Data’ is merely a catch-all category for files that Spotlight cannot assign to specific categories like Applications, Documents, Photos, etc. In fact, what is now shown as System Data used to be reported as ‘Other’, Apple changed the label in macOS 12 Monterey. System Data probably sounds better, but Other was closer to reality. 

How to reduce SYSTEMDATA size by disabling Connection Activity Log in Email on Mac?

Welcome to Apple Support Community
A forum where Apple customers help each other with their products. Get started with your Apple Account.