What happens to the @mac.com (and alias) when I change my AppleID email address?

Update: Changed AppleID email address to a third-party provider. Apple support gave me half a dozen different stories about what would happen to my @mac.com address. Turns out the email address doesn't go away—you can still access it (defeating the purpose for me to get rid of it to get rid of a daily avalanche of obscene spam) but you can't get rid of it, or all the @me.com or @icloud.com "aliases" that Apple assigned way back when (not the email aliases you can create yourself—those are a different "alias."). As long as you keep the same AppleID, those email addresses are yours—all 3, 5, 7 of them you never chose, whether you want them or not.

But rest assured you'll get a different answer from Apple support every time you ask this question!

Thanks for your answer, though it’s not an answer to my question. If I change my AppleID email address to a third-party address (like gmail, etc), and the old address is a @mac.com email, does that old @mac.com email continue to exist? Or does Apple delete it? In other words, this email address that I have had with Apple for years, which was my original AppleID, if it’s no longer my AppleID, does it cease to exist? Or will it continue as a standalone email address, now no longer associated with my AppleID?

Thanks for the reply, but no, that's not what I am asking.

When I first became a Mac customer, way back in 2007, I received an email address from Apple, the name@mac.com email address. That's been my AppleID email address for the past 16 years. Now I want to change the AppleID email address to a different email address, with a third-party email provider, but I would like to maintain access to the name@mac.com (and its aliases) once it is no longer being used as the email for the AppleID.

My question is, if I change my AppleID email address to something else, let's say name@gmail.com, will Apple delete the name@mac.com email address, effectively eliminating the name@mac.com email address? Or will the name@mac.com email just become a freestanding Apple email address that I can continue to use, even though it is no longer my AppleID email address?

I understand that my purchases and text messages, etc., and my access to iCloud, will transfer to the new email address. That's not an issue. Apple has explained that very clearly. What they have not explained clearly (I have gotten more than two different answers from Apple support, so that's why I'm asking here, to find out if anyone else has actually done this) is whether they will eliminate that name@mac.com email address if I am no longer using it as my AppleID.

Obviously, if my AppleID email were already a third-party email (something@gmail.com), Apple would do nothing about that since they have no control over third-party emails, but since this email was issued by Apple as part of the creation of my original AppleID, I want to know that if I stop using it as my AppleID email address, will it vanish into thin air?

Thanks!

Don’t all my purchases and messages stay with my AppleID account under the new email address? Why would they stay with the old address if they are attached to the AppleID?