Is it ethical?

[Aurelia]

Okay, there are worse things in the world to be concerned about, but this nags at my conscience: when you receive a letter in the mail, and the stamp hasn’t been cancelled, is it permissible to cut it off the envelope and reuse it?

 

[Michelle_Arnold]

Someone who reuses an uncancelled stamp is availing himself of services for which he has not paid. It’s a form of petty theft. So yes, it’s unethical. It is also illegal.