My impression was GDPR says you have to give people a way to unsubscribe from your emails. But it seems like Apple doesn't give this option (I don't see an "unsubscribe" link anywhere on the email).
Is this legal?
The CAN-SPAM Act makes it illegal to send spam email, which is roughly defined as non-transactional email that doesn't allow opt-out. (In fact, I think it's a little more stringent than that.) The penalty for violating the act is something like $50,000 per email.
While you can't bring a lawsuit against any company for violating this act, you can complain to the FTC, who is tasked with enforcing this. At the very least, threatening the company can go a long way.
If enough people know about this and use it, it could meaningfully make a dent in large companies abusing the 'transactional email' system for promotional ads.
I then reported it to the FTC, but as expected, never heard a thing.
I've seen the issue you mention with Delta and other companies. I make it clear to them that my interpretation of this law is that membership does not magically make promotional emails transactional.
Similarly, making a purchase on Amazon doesn't magically let you repeatedly send me ads (in the form of "limited time Prime Music discounts that come with your digital purchase").
1. First: if an email contains "unsubscribe" it is very likely automated/promotional.
2. Then: I found common replyto addresses following the same line of thought. (Like "noreply," "info," and even "hello.")
All these mails are tagged with "sub" or "fyi" and automatically moved out of the inbox. (Tip: you can also apply filters to mail you have already received.)
I don't get notification when these mails arrive, but I can check them and mark them all as read in batch with a few keystrokes.
System Settings > Click your AppleID > Name, Phone, Email
You should see buttons to turn off emails from Announcements, Apple Music etc., and Apple News Newsletter.
Arguably, logging into your account is as easy as signing up (by making an account and entering your username and password).
If you believe otherwise, you could consider filing a complaint with your local DPA if you live within the EU and want to make a GDPR complaint.
Also check your local laws; some countries mandate unsubscribe links, others just imply them, but there's no EU-wide law about unsubscribe links specifically. It'd be foolish for a company to not include such links, unless they're using different email templates on a per-country level to comply with the law.
Regardless of legal obligations, this is a horrible business practice I would expect from desperate drop shippers, not an ultra wealthy megacorp like Apple.
If you use commercial services like Gmail, you can report emails like these as spam. The only way to make Apple care about this stuff is to affect their deliverability and that's exactly what the Report Spam button does.