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As even PayPal themselves acknowledge, PayPal users are subject to a lot of phishing emails. So it's odd to see a definitely legitimate PayPal email with a bunch of things you'd regard as pretty strange.
Odd header. Looking at the headers of the message, we can see it's DomainKeys and DKIM signed, but then you have a header like:
Maybe they're giving away a bit much information about how they feel about the emails they're sending you
Invalid links. The top of the email contains a "Transaction Id: XXXXXXX" item, with the id itself being a hyperlink. Unfortunately the hyperlink is wrong, and has an href of:
So clearly the hostname was accidentally left out.
Mixed case inline URL. The message contains a URL to their help page, but the URL isn't a hyperlink, it's just text, and they've marked up the URL in a very odd way. It looks like:
Questions? Visit the Help Centre at: https://SECURE.UNINITIALIZED.REAL.PaYpAl.CoM/au/help
Put altogether, it's a very odd email to receive, and took a moment and a closer check of the headers to believe it was legitimate.