Katharine Spencer-Brown, from Kettering, was checking her emails on Saturday when she came across the message.

The email, sent from the address deadlykillers61@gmail.com with the sender name 'KILLLLLL', said: "My duty as I am mailing you now is just to KILL you and I have to do it as I have already been paid for that.

"Someone you call a friend wants you Dead."

The message goes on to say the sender will send his "boys" to track the recipient down and that he knows the recipient's name and has a photograph of them.

The recipient can prevent their killing by paying money to the senders, the message says – but it also warns: "Do not think of contacting the police or even telling anyone because I will know".

Ms Spencer-Brown reported the message to Northamptonshire Police.

The spam email is believed to have been circulated widely and it is reported to have been received by internet users all over the world.

Police forces who have dealt with it in other parts of the world have dubbed it The Hitman Scam.

Ms Spencer-Brown said: "I am sure it could really frighten some people so when I reported it to the police they said it was definitely a scam.

"I did a search online and found lots of reports about it.

"The police told me to delete it.

"I would encourage people to report it to the police if they receive the message and definitely not to reply, because if someone does that the person who sent it will know someone is reading it and could potentially send more.

"It was an awful email – I just want people to know it is a scam and not to be afraid or feel intimidated by it.

"It would have been awful if my 12-year-old daughter had received it, not me."

A Northamptonshire Police spokesman said: "We can confirm Katharine Spencer-Brown contacted us and we issued her with some advice."