i dont know if its for sales or to tag houses for breaking and entering later. If people dont take the sticky notes down in could be assumed they were out of town. I also got one today on my mailbox. I called the number with a blocked caller ID and it just said mailbox was full.
Mine also had the name Shawn on it. The first part of the message definitely looks preprinted.
The phone number and name look like third grade penmanship.