he sent me this message:

[21:08] Master: SPECIALLY FOR SOLDIERS INC! Right now, for a limited time, only for Soldiers, buy the 50 level 15 friends for your Recruitment Depot rewards, and get thousands of defense troops to protect your base ABSOLUTELY FREE! And as always, you pay AFTER you receive what you order. Check us out today at www.Plarium.site

the player is located at -45 / 2100

that looks like phishing/spam to me.

That plarium "Pirate" site is sending out mails to random players all the time.
Plarium is always watching what you are writing inside the game though..
If you as much as write that adress within the game plarium will close your account within a minute.
It happend to me and it took over 24 hours of communication with support to get back access to my account and all I did was trying to ask in chat if I was the only one that had got mail from a player called "Friend" and as it was new to me I just wanted to know what that was about.

Just so you know  all "guest", "unknown", "friend", "master" and so on and on, are all from that "pirate site" and having them on your team does most likely not benefit your team.
Considering what they are offering they must have hundreds if not thousands or tens of thousands of bases, castles etc. in all games together.
So plarium knows very well what that site is and that it is a "pirate site".
Why plarium is not just deleting all the accounts that site is creating beats me.
..I mean it cant be that hard to delete them if plarium wanted to, as they just use same name and a number after on all accounts.