Those characters are unicode, which is why they don't show up in preview. The same is true of any unicode, such as custom emojis like this one - 😀
But why would people with bad intention do it? Wouldn't it makes the email more likely filtered by spam filter feature?
Possibly the opposite depending on how advanced the spam filter is. By making it unicode, it's possible that a lot of the more basic "keyword" type spam filters will be unable to actually scan the message.
It is a strange tactic tho... because it seems like their instructions to copy/paste and remove the ^^'s might fail if you try and copy/paste the message into apps that don't support unicode characters etc.
At least it's useful for Ledger customer who're not affected by previous data leaks and future Ledger customer, assuming they actually and successfully do it.
And also something they should have been doing from the very start... or at least encrypting stored data

They should know that... I mean, they work in the "
cryptosphere" FFS!
