How can I block emails with no sender?

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The only remedy I came up with was to go to my internet provider (Spectrum) and dive into my email settings there, marking one spammer with no email return address as "junk mail" and they automatically moved all of them to the junk mail folder. When I returned to my Mac's email page, they were all in the junk mail folder as well. I hope this solves the problem.

Haven't tried this with Apple Mail.

Some Windows users were having the same problem with "No sender" spam, and someone came up with the idea to set their mail filtering to move ALL e-mail into (a junk folder, or the trash), EXCEPT for e-mails where the sender field contained a '@'. The idea being that all legitimate e-mails (as well as many others) would have the '@'.

https://answers.microsoft.com/en-us/outlook_com/forum/all/how-can-i-block-spam-email-with-no-sender-email/1ad8e13e-8dc9-4d7f-9b7c-24217094ec3b?page=1

I have the same (or similar) problem, but there is just one piece of text in every one of these junk emails - a 'Remove-Me' at the bottom with a link that I'd never click on. I set up a rule to delete anything with 'Remove-Me' and that works.