You may mail items to Neumann Library. You should probably insure them, just in case.
Address mailed items to:
ATTN: Circulation department
Neumann Library, UHCL
2700 Bay Area Boulevard
Houston, TX 77058
You may also return books belonging to UHCL and other UH System libraries to any of the University of Houston campus libraries, if one of them is closer to you. The one exception is Interlibrary Loans (books that belong to libraries outside the UH System), which need to be returned directly to UHCL.