cannot delete no sender emails onI imac

If the e-mail account issuing the IMAP Protocol

Log into the Web Portal of the e-mail account using the Web Browser of choice

If it is appearing there, remove it.

What appears on the Web Portal using IMAP will be reflected back into the Mail application.

An Yes, update the computer to the current version 13.6 of Ventura

Links below

About the security content of macOS Ventura 13.6

About the security content of Safari 17

Keep your Mac up to date - Apple Support (CA)

RK from OZ wrote:

The offending emails have magically disappeared. I did check my webmail, none there. My iMac wants to update Sonoma 14.0.

Should the problem resurface, I'll go back to your suggestions. Thx

Good to know and thanks

I recommend you update to Ventura 13.6. Then test to see if you can remove those emails.

Time permitting, let us know the outcome