You are fine.  Dell-Cares is a Dell tool used by Dell's employees.  It will ask the service tag to check for machine warranty status.  No trouble at all.
I gave my service tag in private email to a user named Dell-Cares? I don't know who he/she, i assume it was a message from dell with name like that. What to do?User: [URL]  What does this service tag even do? Am i in  trouble? Is this a dell support employee?
Some one asked my device service tag the user for a question i posted earlier, 
i think?