The book is a university text book.

It has a big U on the page just inside the cover.

http://i116.photobucket.com/albums/o14/Yanky_Say/3-31-201121312PM.jpg

The U bled to the page in front of it which has no text and that's the only page that it's on. No writing inside of the book.

On top of that, it looks like because this is a used school text book, the school glued an extra sheet from them to the front page. This only says congratulations on it and gave me access code to something which I didn't scratch off yet.

Yes, I think it is postable. Writing is OK on non-text pages, and in any case, that looks like some kind of bookstore mark.

Should I PM about the extra sheet though? Cause you can see the glue.

Well, IMO, it would probably be considered a "sticker", which is allowed. Also similar to library stamps and stickers. So I think its fine, too.

Alternatively, you could probably trim the page right out of the book if you think it will cause an issue.

Because books are postable even if they are missing non-text pages.

I would also consider that postable.  You may use the texbook waiver if you wish (to disclose the marking), but in the case of a true textbook...considering the cost and your clean text pages, I'd be surprised if a wisher declined.

 I think it is postable, just be sure to PM the person requesting it first!