I bought a Rattmotor 2.2kw spindle from Amazon, grounding

Hi, bought a spindle from Amazon because I bought one from ebay and then a week passed and then they refunded me the money so I paid the extra to get next day. Seems a lot better quality than the last spindle, better sockets, weighs 1kg moor and feels better machined,

They sent me this message

Attachment 29919

The only thing I already probed the 4 pins and there is continuity between pin 4 and the body so I cracked the aviation plug off and this has a proper GX25 on it rather than the custom 20mm they normally have and low and behold there's an earth wire connected to pin 4 going into the spindle body somewhere I couldn't see where

pins 1, 2, & 3 have no continuity to the body only to each other

So it's actually grounded even though they emailed specifically to tell me it's not, right?

And I should connect pin 4 to earth?

Of course, it's a safety thing. The metal case should be connected to the protective earth (PE) and not to ground, which is normally the DC common. Same as your iron which you use for ironing your shirts with.

You've purchased it finally from Amazon and returned that one from eBay? Did I get it right? I mean, you're satisfied with the Rattmotor from Amazon?