The most egregious part of this April fools joke is the use of minions. The only thing I am capable of thinking of when I see a minion is the absolute most common soccer mom in the world interacting with the 'internet'.

It is the last thing I want to see in an email, business or personal. Let alone at the top of an email. Let alone at the top of an email I cannot respond to. If I can't respond to it, I don't want to see whatever it was no matter what it was.

Not a good idea, minions aren't funny. If Google hadn't screwed with the standard behaviour of their email product it's still not a good idea.