like other people who have responded i too sold vinyl records back when i first started on ebay. 

my only suggestion to add is that if you do decide to purchase vinyl record LP mailers - it's better to get the ones that fold into a small box, rather than the flat cardboard ones. 

the flat cardboard ones are still very prone to breakage won't withstand AP's handling of parcels. especially since they don't recognise "FRAGILE" labels / stickers. 

i always found that the foldable box LP mailers gave the best security, providing you pack both sides with either bubble wrap, cardboard, tissue paper etc to restrict movement of the record inside the mailer during transit.