Memory leak for Mail App - now on Sonoma 14.5

I have used Mail ever since 10.2 Jaguar, some 22 years ago. I have POP, IMAP and Exchange accounts, several hundred mailboxes and many thousands of messages, and I never saw the problem you are experiencing.

There is certainly some other piece of software involved, something local to your machine.

As PRP_53 recommended, please run Etrecheck and post its full report here. Use the "additional text" button and paste the report into the text box.

Also, do test in Safe Mode. I would be very surprised if the problem were to manifest itself while in Safe Mode.

If it does not, then for sure some third party software is involved.

... looks like I need to try something more drastic, but I've already installed the OS from scratch once,

Did you test it before reinstalling all of your system modifications? Also, it does sound like "from scratch" means you erased the drive and reinstalled, but if you only reinstalled macOS that doesn't remove the system modifications.

If you reinstalled on an erased drive, then used Migration Assistant, you brought back all of that stuff.

Can say with great certainty.

On 3 different Apple Computers ( 2 Desktop and 1 Laptop )

All 3 running Sonoma 14.5 with Apple Mail Client

Do not experience any " Memory leak for Mail App "

To avoid the question / answer and question answer scenario and drill down on this issue.

Restart in Safe Mode. This will perform a Disk Repair, clear cache files and only load Apple Software, extensions and fonts. The boot up will be slow and can take some time - Normal.

Safe Mode will also eliminate Third Party Software, extensions and drivers from loading. It will only load the Minimum amount of Core Apple Processes to allow the the computer to function at a reduced Level of Performance 

Does the issue present in this mode ?

Sometimes a Safe Boot followed by a Normal Boot will just put things right.

If not - there could be something in the main User Account playing up. To further isolate this - Set up users, guests, and groups on Mac. Then log out of the Main User account and log into the dummy account and test again if the issue persists.

If the issue is present in the dummy account - then, this appears to be a System Wide issue on the computer.

Download the Application Etrecheck  ( External Link ) directly from the Developer.

The Application is Not a " Silver Bullet "  and is  only a tool to examine the Hardware / Software used on this computer 

This is a Diagnostic Tool that makes no changes to the computer Hardware / Software used on this computer 

The application is free or paid from added features. 

The Report will Not Reveal Any Personal Information. 

Post back the Full Report - copy and paste - >>>> using the Additional Text Icon ( 3rd Icon to last ) <<<<

Lastly - should you decide to use and post the Report now or at a later time, we are willing to have a very close look and offer some insights 

Thank you for posting the report. The system seems relatively clean. I cannot see anything that might contribute to the problem except perhaps the darn google “helpers”. These keystone agents are very badly programmed and at times grab system resources, causing other applications (especially video applications) to fail miserably. I have not seen them affect Mail, but would not put it past them.

I would try completely uninstalling all the keystone and google anything, and see how Mail behaves after that. If the problem persists and you really want to use Chrome (despite being a data syphon as well as badly programmed) you may install it again. Note that it us NIT enough to drag Chrome to the trash; you have to remove all those background tools. For more information you may see https://chromeisbad.com

UPDATE - just upgraded to Sonoma 14.5. Was hoping that would fix it. Nope - opened Mail, with zero accounts, no saved messages, nothing - and in less than 60 seconds it was using almost 50GB and everything froze until I force quit.

Uninstall all of your System Modifications using the developer's uninstaller and test.

Would have replied sooner but not getting the Auto Notification from Apple regarding a New Posting in this question.

That is an Apple Issue I will pursue with them, again.

How to erase all content and settings

I would be strongly after that is done.

Do Not use Migration Assist.

Not until you have done some serious Testing as to whether the Mail Client is acting up or work normally.

This would be a very good Test to see if any Third Party Anything is or could be the Root Cause if this issue

Add On

Right now on a M3 MBA with Sonoma 14.5

Have Safari and Apple Mail Client open and nothing more

One email account in Mail and using 55.3 MB of Memory which is very normal

A singular reported and captured occurrence of the Apple Mail Client does not support the contention of a Memory Leak

To support such a contention of a Memory Leak, would require a much more that 1 one off occurrence

Sonoma 2024-05-29 macOS 14.5 (14.5)

Diagnostics Information (past 60 days):

2024-05-29 02:01:58 Mail.app - High CPU Use

First occurrence: 2024-05-29 02:03:29

Executable: /System/Applications/Mail.app

Follow on

From the report

Hardware Information:

    MacBook Air (M1, 2020)

        Status: Supported

    MacBook Air Model: MacBookAir10,1

  ➡️  2.40 GHz Apple M1 (m1) CPU: 8-core ⬅️

    16 GB RAM - Not upgradeable

    Battery: Health = Normal - Cycle count = 265

Have never seen the 2.40 GHz Apple M1 ( m1 ) being reported

Guess this is unique ?

Below from a M3 MBA I own and operate

Hardware Information:

    MacBook Air (13-inch, M3, 2024)

        Status: Supported

    MacBook Air Model: Mac15,12

    Apple M3 CPU: 8-core

    Battery: Health = Normal - Cycle count = 3

Sorry ** one mentions log files

Which log file is showing the “ Memory Leak “ ?