What should I NOT do when returning my test sample?

Do not ship your sample on a Friday or the day before a UK Bank Holiday. Do not put your DHL return label inside your box or packaging. Do not ship your sample without a box. Do not place any requisition forms in the outer side pocket or loose inside the DHL shipping bag. Do not obscure the UN3373 diamond, heart symbol, pink line with TDX wording, Biological substance  category B wording, OVERPACK wording, MEDICAL EXPRESS wording, or DHL EXPRESS wording on the label.