But no one should need to know this. I don't know what's so wrong about just using google.com, or even .google for anything user facing...
I understand the idea that they want an official TLD that doesn't necessarily have their trademark in it, so you know it's a link to a Google service but potentially user content, but why have c.gle links to official/urgent messaging??
(at least they don't use 1drv.com in emails like Microsoft.. seriously...)