I've just put an order of books in a tea-box (a box that held tea-bags) that was used to ship coffee to me from Canada. There is writing (as in the name of the tea, etc) on the outside of the box. Do I need to wrap the box in brown paper or can I just tape it up and put the label on the top of the box as I would a regular brown box?

I thought one time when I went to ship something, the guy at the post office said I didn't need to wrap in brown paper but I can't remember--it was along time ago!

i send books out in boxes all the time. ive used cereal, mashed potatoe, and even the big cheese-it boxes. i think the only ones you cant use are like bleach or beer/alcohol boxes

I usually do just to make it look more like a box. But I have received ones that weren't wrapped.  I got books in an orange juice box like from Costco and a cereal box. I even got some wrapped in an outdated road map.  I've sent them in cereal boxes and once I used a box that held my Pilates ball. Sorry I did that now because I moved recently and still can't find the deflated pilates ball. 

I think Stephanie is right though about not using anything with hazardous materials or liquor.  Anything that might be deemed flammable or toxic without covering it up. 

Also do not reuse prioriity mail boxes or envelopes.  They don't allow that.

I think they prefer if you mark out the markings.

I mark out or remove or cover anything that looks like a postal address or bar code.  Have had no trouble reusing either boxes, envelopes, or papers like bulletins or newsletters.