What is the schedule? For importing prescription or regulated substances there are usually minimum allowances made. I believe anything over a 3 month personal supply is seized, if they happen to come across it that is. DHEA, pregnenolone, insulin are some things that will come through. As long as you aren't ordering 30 bottles you stand a chance. Then again I once imported 15 boxes of anastrozole and received it successfully, so it's also about how lucky you are. Worst case scenario you get a letter saying "don't do it again".
You can order up to a 3 months supply of certain prescription drugs and pharmacy medication online and customs won't seize it.
I'm pretty sure this excludes anabolic/androgenic compounds. So ordering aromatase inhibitors is fine but not steroids.
I could be wrong though.