Mac Mail can't receive specific mails that I get OK on iPhone

Using the Mail app, my Mac is unable to receive a couple of email IDs that show up just fine on my iPhone and iPad. Junk Mail Filtering is enabled, but set to "Mark as junk mail, but leave it in my inbox." Mail from those problem IDs, however, doesn't appear in either the inbox or junk folder, even though it shows up on the iPhone & iPad. That means it can't be iCloud filtering and must be specific to the Mac.

I also use Rules to automatically delete suspicious emails from domains in other countries (.ru, .it, etc.). In the Mail app, when I searched for one of the problem IDs, I got a dozen or so matches, but they were all from 2014 or earlier. There must be some file, probably a hidden file, that contains these problem IDs and blocks them. I tried using Finder to search, including hidden files, for one of the problem IDs, but there was no hit at all.

I might just ignore this problem if it were just a friend, telling him to send to my wife's ID and having her forward his email to me. But now I find that one of the problem IDs is used as an alert from my bank. Missing an important alert could be serious, because I rarely check email on my phone.

I'm out of ideas and hope someone can help.