Preparing registered mail

• Preparing registered mail?
• How do I put the address on registered mail?
• Where do I put the address on registered mail?
• What is RP?
• Do I need to tick the RP box?
• What formats are allowed for a registered letter?
• What is the maximum weight for a registered letter? Standard vs non-standard mail format
• How do I hand off my registered mail if I don't have a red bag?