from Wiktionary, Creative Commons Attribution/Share-Alike License
- Sealed With a Loving Kiss, term of endearment written across the seal of a love letter.
Sorry, no etymologies found.
I also believe it's traditional to write SWALK on the back.
you're too young and trendy for me by far - don't understand half the stuff you're talking about whatever happened to good old paper and pen, envelope, stamp and SWALK?