Off-Topic Forum

Today I received a trade in the mail that was a long time in coming.  I believe it was late because it was flagged for some reason.  There was a yellow sticker on the envelope that said "unable to forward / for review".  A quick google search led to me learning this is used when mail is sent to an old address with no forwarding.  However my address was correctly written and I have not recently moved.  
 

Does anyone know why this might have happened?  Is it a frequent occurrence or a fluky thing?  I know there are postal issues galore.

Thanks

Because machines read & sort the mail, not humans.  I've had mail returned to me "unable to forward" but there was nothing wrong with the address. I just pulled the yellow sticker off and put them back in the mailbox.  They all got delivered.

As a full time postal employee I have seen this happen when a letter, such as yours, is given to the wrong route to be delivered. The carrier is supposed to put the mail in misthrows so it gets resorted to the proper route. In some cases though, I believe, they accidently put it in the forward mail. When it gets processed, because you don't have a forward, it gets the yellow sticker to go back to the sender. Yours must have gotten the sticker, but made it to the proper route, where it was delivered to you. I see this happen a lot, when substitute carriers get a piece of mail they don't know what to do with, so they just stick them all in the forward mail, assuming they will get resorted back to the right route. It's mostly due to their laziness and unwillingness to turn the letters over to the proper area for resorting or delivery. Not saying that is what happened, but sounds like it to me.