First tell them not to contact you anymore and save the previous email. If they contact you agin you can report them. Email harassment is a crime, If you ask anyone not to contact you, legally, they MUST comply
I do not think you should respond to a threatening message and if they know any of your personal details you should call the police.
The doctor or nurse should be consulted prior to responding to incoming messages from patients. Incoming messages should be responded to promptly by telephone.
If you're worried enough, You tell the police, and give them copies, or show them the messages.
If it clearly is life threatening if not then no
Yes absolutely.
SPAM
A simple "Thank You" is enough.
Not respond with appropriate actions
The reason a lot of Turkish girls won't respond to messages on Facebook is because they do not like the person or the messages they are receiving. -- It has nothing to do with them being Turkish per se. Most girls behave this way.
Receptores.
All I can think of is to say something threatening to someone. I wouldn't recommend it
By threatening to use crushing, overwhelming force and nuclear weapons.
No they cannot