Always use USPS, it is much harder for them to have the right to open your package. The private couriers can do whatever they want once they have possession of it.
I think if you are mailing weed a foodsaver or other true vacuum sealer is a must! It will really cut down on smell. An idea I have been kicking around is a double vacuum seal with activated carbon. Put the weed in one bag and seal. Put that bag in a lager one and add a good amount of activated carbon then vacuum seal it. Its probably overkill but I think activated carbon could be used with quite a few other shipping methods to keep down on smell.
I think if you are mailing weed a foodsaver or other true vacuum sealer is a must! It will really cut down on smell. An idea I have been kicking around is a double vacuum seal with activated carbon. Put the weed in one bag and seal. Put that bag in a lager one and add a good amount of activated carbon then vacuum seal it. Its probably overkill but I think activated carbon could be used with quite a few other shipping methods to keep down on smell.