Why is Apple Mail not showing content of many of the emails I receive?

The permanent fix revolves around More RAM, Bigger Hard Drive, and fewer open Apps most likely, but to get a better idea...

EtreCheck is a FREE simple little diagnostic tool to display the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to help people help you with your Mac. It will not display any personal info.

https://www.etrecheck.com/

Thanks for Old Toad’s etrecheck instructions…

https://discussions.apple.com/thread/255121100?answerId=259529290022#259529290022

Use the Note tool on the bottom of this editor's toolbar, as shown in the image, to copy and paste the output from EtreCheck. In a Reply before you click post, look for this to add longer texts...

Start with this of M1 or M2 Mac...

On your Mac, choose Apple menu  > Shut Down.

Wait for your Mac to shut down completely. A Mac is completely shut down when the screen is black and any lights (including in the Touch Bar) are off.

Press and hold the power button on your Mac until “Loading startup options” appears.

Select a volume.

Press and hold the Shift key, then click Continue in Safe Mode.

The computer restarts automatically. When the login window appears, you should see “Safe Boot” in the menu bar.

Restart normally.

If you have no POP accounts & they’re all IMAP accounts then in Mail’s Mailbox menu choose Rebuild.

No easy fix. Read through this discussion:

https://discussions.apple.com/thread/254504347

Hello there.

Any fix for this ocorrence?

The suggested procedure fixes the problem temporarily, bit whenever (in mu case) I reboot it rehappens.

Help !please tell me how to