Mail using 200%+ resources

Hi Luis. Thank you so much for your quick response. I downloaded Entrecheck and ran it. The report was too long to paste in (over 5000 characters) so I made a text file and attached it for you. Many thanks. Warwick Dipple

The problem is on your computer. There is no problem with Mail. Try downloading and installing the MacOS Catalina 10.15.2 Combo Update. See if that helps.

If reinstalling the combo update for Catalina did not help, then you have this option:

Install El Capitan or Later from Scratch

If possible, back up your files.

1. Restart the computer. Immediately, at or before the chime, hold down the Command and R keys until the Apple logo and progress bar appear. Wait until the Utility Menu appears.
2. Select Disk Utility from the Utility Menu and click on the Continue button.
3. When Disk Utility loads select the target drive (out-dented entry w/type and size info) from the Device list.
4. Click on the Erase button in Disk Utility's toolbar. A panel will drop down.
5. Set the partition scheme to GUID.
6. Set the Format type to APFS (SSDs only) or Mac OS Extended (Journaled.)
7. Click on the Apply button, then wait for the Done button to activate and click on it.
8. Quit Disk Utility and return to the Utility Menu.
9. Select Install OS X and click on the Continue button.

You can restore your data from your backup. Only restore data that belong in the default folders in your Home folder. Do not attempt to restore the /Home/Library/ folder's contents because that is probably where the problem lies. You will have to recreate your email account in Mail.

This happens to me with alarming regularity. Activity Monitor shows Mail uses 99.9% of the CU and freezes. Except Mail still crashes every other day. It has being doing it for about 12 months now on my iMac. I was delighted when I updated to Catalina and love the upgrade. Except Mail still frequently loads the CPU at 100%. How com no other software does this? How come it only ever happens with Mail open? I am very meticulous about filing/deleting my emails and the mailbox is never very full. It has just happened again. I vae taken a screen grab with Activity Monitor open.

So there's a rogue process going on with the computer and I am expected to risk going through this process myself to fix it? How come this is my problem. Alternative is to take it to an Apple Store and let them take the risk. Thanks for your advice I do appreciate it but I am a user of this product and not a technician. :-(

The report is pretty clean, no obvious bad actors.

Is there any particular action that appears to correlate with the spike in CPU use (e.g. checking mail, sending...)?

Do you have a great many different mail accounts?

I have four different accounts associated with Mail and I have never seen this behavior.

Hi Luis,

Just the one account: warwick@wddesign.co.uk

I leave mail running while I am working on another iMac 27inch.

This iMac only really checks Mail and Safari, so it isn't under any pressure.

It's set to check mail automatically every 5 minutes.

I will leave Activity Monitor open and see if I can spot any spikes.

Thank you for your help. Much appreciated.

Best regards, Warwick

Please run Etrecheck and post its full report here.

There is something specific to your setup causing the problem and the report may help us find out what it may be.

Just remembered, it sometimes happens when I save attachments to the iMac27" via Ethernet connection.