My app-specific passwords for my iCloud.com email have stopped working. Why?

I've created app-specific passwords for an iCloud.com address addition to my Blue Mail account with the format name.server@icloud.com, over and over again, Each time, Apple verification fails -- also, over and over again -- because, according to Apple, "user name or password are incorrect,." But of course they are correct, because they are hot off the Apple server. Have you had this problem?

ll this Apple Spy vs. Spy stuff is more maddening than dealing with actual exploits, which are far fewer in number., even quite rare. Is this really the best way to prevent application pirating? But given that this is what it is, how do I deal with iCloud's recurring errors?