They come after signatures in snail mail

• Some scribbles, for short
• They may follow signatures: Abbr
• Letter addition letters
• End-of-missive extras, for short
• Addenda to ltrs
• Supplementary words in a letter
• Written afterthoughts
• They're not part of the body: Abbr
• Letter closers, briefly

Wikipedia Word definitions in Wikipedia
PSS may refer to: