>>>Hey everybody,
>>>
>>>are you aware that today is a very special day? In Europe we use dd-mm-yyyy for dates, so today is 22-02-2022. If you remove the dash, you end up with 22022022 which is a palindrome. So, happy palindrome day, everyone.
>>
>>Not exactly everyone, there are the Americans...
>
>I don't think it's proper to write "Happy palindrome day, everyone, except Americans"...

The proper form says „...to all who celebrate“. It's become customary here. Even internally, in my family - we have two tworthdays, i.e. shared birthdays - there a pair of twins, and then our oldest daughter is exactly 24 years younger than me (IOW we are both 43 this year, though in my case it's actually 0x0043), so „happy birthday to all who celebrate“ makes sense in our context.