I reused an illustrated envelope (from the Philatelic Service) to send a letter to Heleen (the Netherlands). The Mafalda stamp (top right) exists as a real stamp. But it has no value impressed on the envelope.
I looked for stamps featuring the globe to match it.
This letter took two months to reach its destination.
This letter took two months to reach its destination. 
And it got a couple of postmarks on both sides!
