How can I block emails with no sender?

Thanks for your reply, ku4hx. Unfortunately, I cannot make any selection in Mail>>>View>>>Message. All selections are greyed out. "All Headers" is greyed out. "Raw Source" is greyed out. "Show with light bqackground" is greyed out.

Thanks again ku4hx. For me, an OS re-install is just too risky. For me, OS upgrades tend to cause problems. Of course a re-install is not an upgrade but nevertheless I am reluctant. I am also skeptical that an OS re-ionstall would help anything. If I was comfortable with OS-reinstalls I would probably just do it.

Another reason I don't want to try an OS re-install is because I belieive this problem (cant block "no sender" emails) is a known problem with Apple mail. The thread I referenced is at least a year old. But on that year-old thread there are no useful solutions provided by Apple Support. So I suspect this is a known bug and Apple Support just doesnt want to acknowledge it publicly. I can't think of any other reason why such a simple question would go unanswered for so long. I suppose another reason why the original thread has not been answered is because it's a bot answering with no human supervision.

No, there is no common text in the body of the emails that can be used to create a rule to remove the emails. The emails I am getting are spam advertisements. They are all different. The "no sender" is an email exploit that spammers are using to bypass junk filters in my Apple Mail app. The only question at this point is whether this problem is caused by my old hardware that can only pgrade to Big Sur 11.6.5. I suspect that since Big Sur 11.6.5 is no longer supported by Apple, and that since the "no sender" spam exploit is recent, then I may have no solution. This bug could be easily fixed by Apple and this bug probably already has been fixed by Apple in the lates macOS updates. Probs I am out of luck because Big Sur 11.6.5 is no longer getting updates by Apple.

Very Interesting. It never occurred to me that there were only two people with this problem, me and the original poster in my thread above. I saw the "me too" button and assumed there must be more, perhaps mistakenly. I did some more checking around and found this: (No Sender) e-mail - Apple Community

which is macOS 13 Ventura. So more than two users with this problem but still apparently very few. The above Ventura thread ends with a Level 10 support person attributing the "no sender" problem to anti-virus software. anti-virus software is apparently nothing but a scam for macOS. i don't have any anti-virus softare on my machine. I will try the Product Feedback---Apple link.

Old Toad, I don't understand. Keyboard Maestro looks like a tool to create keyboard shortcuts. I get one "no sender" email every day. If I want to delete that email I make two clicks, one to select the email and the second click on the trash icon. So that's not many clicks to delete. I guess you could get it to one click with a custom keyboard shortcut, like shift-comand-alt-x-select or whatever. Are you suggesting my two click process could be improved to one click or are you suggesting something different?

"what the heck" indeed. As I mentioned earlier in this thread, https://discussions.apple.com/thread/254567622, I found a MacOS Ventura 13 user who has the same problem. Maybe this problem is present in all MacOS or maybe it somehow turns up only infrequently, I don't know. But the simple fact is that it is not a sufficiently high priority for Apple to fix, perhaps because the software bug only turns up for a few users. The problem seems easy to fix as it results when the sender="null" b ut maybe not so easy to fix for who knows what reason.