Today I received five books in the mail out of eight I'm currently waiting on. They were all ordered at different times and the oldest is only a few days from "lost in the mail" status.  It was really weird- like the post office had been storing them up or something.  The one I've been waiting on the longest is damaged.  It was in a manilla envelope with tape at the corners.  No plastic wrap inside.  The package was dirty and a little beat up looking. 

The book has water damage to the back cover and 50 or so of the pages.  Honestly, I don't know if this happened during transit or if the sender sent it in this condition.  The manilla envelope didn't look like it had gotten wet, but I could imagine that if it did it might have dried during its mystery tour around the local post office.  The dirt and wear may be helping to disguise water damage to the envelope.   Being that I'm not sure, should I mark it RWAP by post office? 

If you can't be sure that the book was damaged prior to mailing, I'd give the benefit of the doubt and mark it damaged by the USPS.  Usually you can tell if the envelope's gotten wet but with a beat-up envelope that may have been put thru the mail several times, it can be hard to tell.

What does the inside of the envelope look like?  Is it stained?

Good point, NewRuth.  It doesn't seem to be stained on the inside, so I guess that's my answer.  Funny just yesterday I was saying on the forums I was going to man up and mark things RWAP if needed.  Guess now I'm going to have to live up to the promise.

I would think even if it took a while to get to you-that if it got wet enroute that it would still be damp.  Also if the envelope got wet enough to soak through to the book it probably would have been torn. 

I once sent a package from one corner of Missouri to the other.  The box got torn up and the contents scattered in a USPS sorting station in Trenton, NJ.  My mother ended up with about half of what I had sent her plus things that I had not sent her.  It doesn't happen that often, but the post office can make some whopper mistakes.

If it took that long to get to you, and the envelope looks that bad, I would hang it on the post office.  If they got it wet soon after they picked it up, it would have had time to dry by now.  Maybe they kept it so that it could?  They would have known that to send a wet envelope through their equipment  would have damaged the envelope and probably the contents.  The envelopes they use to say "sorry, we damaged your letter (or small package)" are just plastic bags and they would have known that it would be prone to mildew.

Or you could just ask the sender about it.  That might tell you something. 

Lacking any other evidence to go on, I say blame the post office!

Water does not always cause stains. Only if there is color to leach out of the paper while its wet and distribute somewhere else on the paper. Or if the water has minerals in it that react to substances in the paper. Etc.

When packages are really beat up, I usually attribute damage to the PO, unless its something like cheeto fingerprints ... (cause I know my mailman is NOT doing that!)