All you really need to safely pack a record is:

• LP or 7″ mailer (A bubble mailer or pizza box do not count!)
• Packing tape
• Bubble wrap (optional…but recommended)
• Backing board     

Don’t forget to write FRAGILE on the outside of the mailer too!

Not to mention the miserable summer heat that 99.9% of the time will cause records to warp if they’re left sitting on your doorstep long enough.