I need help on UK payment for Ebay

[yg60m]

Hello, recently I sold a phone on ebay and it was bought by an english people who paid me by Postal Order ( http://www.postoffice.co.uk ) but I have some doubts on this mean of payment, i received this e-mail :

"Dear Yann G**** , Thanks for using Postal Order®, well, this is the right Postal Order®, your money is €***.00, for ebay item#********, and the money is paid in by Miss Mary Smith. Due to the fact that most sellers don't send the item despite the fact that buyers have paid for the item, so we made the policy that sellers must ship out items within 24 hours of payment and send us the tracking number for verification. You are not expected in any circumstances to send the tracking number to the buyer. Below is your address details.if the information is correct pls mail us back. The money will be delivered to you at your door step immediately we recieve the shipment tracking number. ... We are waiting for you to ship the item and mail us the shipment tracking number so that we can send out your payment. Thank you for using Postal Order®. We look forward to serving you online auction payment needs in the future. Sincerely, Postal Order® "

Has someone already used this way for paying/being paid here ?? Is it safe ??

Thanks in advance for your help ... ops: