Is this a scam? Please help ASAP!

Description

Hi there,
I uploaded an item for sale on a Facebook group and a profile, named Gary from Georgia/USA, has popped up saying he will send the money plus pay for delivery which would be £250 plus £100 to cover delivery costs.
I sent him my PayPal email and he then sent me an email which details the following:
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You have received new funds!

Dear Elle .

This email confirms that you have received a payment £250.00 POUNDS from Samuel .
Follow the steps below for your account to be fully credited:

This is a confirmation email that you have received a sum of £250.00 POUNDS paid by our valuable customer. This payment has been approved but will not be fully credited into your account until shipment verification process is complete. We at PayPal now verifies and ensures 100% percent safety for both sellers and buyers to make sure no one looses there funds, Therefore you are to ship out the package that is paid for via Post office and email us with the postage tracking number for shipment verification so as to protect both sellers and buyers. Your account will be credited immediately after the shipment number has been verified. You are to carry on with these procedures so we can complete the verification process, failure to do this will result in the suspension of your PayPal account and you will be charged for Fraudulent activities by our Authorities.
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PayPal Shopping Cart Contents
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Item Name: Dress

Quantity:1

Total: £250.00 POUNDS

Cart Subtotal: £250.00 POUNDS

Cart Total: £250.00 POUNDS

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Payment Details
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Total Amount : £250.00 POUNDS

Currency: POUNDS

Transaction ID: 0PS63413KS1681107

Delivery Insurance: £0.00 POUNDS

Buyer: Samuel

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Delivery Address:
Name : Samuel
Apartment #:

United States of America
Have you lifted your withdrawal and receiving limits? Just log in to your PayPal account and click View Limits on the Account Overview page.

Yours sincerely,

PayPal _____________________ He is now demanding that I send the item (which is a wedding dress) and he has said: I have already transfer the fund to PayPal to your PayPal account and it has been deducted from my account you are required to get the item shipped out first and send them the tracking number to pay pal so they can verify and proof the shipment from you and once they receive the tracking number they will credit your account. Can somebody please help?!