Wrap your LPs in bubble wrap and tape the wrap around them so the wrap is a snug cushion around the records.
Insert the LPs, no more than two at a time, in a Priority Mail box or envelope.
Fill the remaining space in the box with bunched up newspaper or bubble wrap so the records sit securely inside the mailer box. This will prevent the records from moving around inside the box.
Pay the postage fee and get a tracking number to track your package and get confirmation when it has reached its destination.