California Gov. Gavin Newsom signed a new law on Wednesday that aims to stop other states from prosecuting doctors and pharmacists who mail abortion pills to patients in places where the procedure is banned. California already has a law protecting doctors who provide abortions from out-of-state judgments.
I would think that if they are sent by USPS then the states would not be able to legally intercept them. USPS is not responsible for enforcing state laws and there are some pretty serious laws protecting the privacy and integrity of your parcels and mail.