At Svalbard Global Seed Vault the storage temps are 0 F and if the facility has a mechanical issue the permafrost will still keep the stock frozen and secure . I do also know many breeders and preservation growers who store all seeds in the freezer . But with that said the general rule in the industry is freeze once only . All bets are off in they are refrozen .. I do not really believe this rule as Nature can and does subject seeds to random thaws many times during the changing seasons . I used to skip school and travel down into Indiana to collect ditch weed , good old industrial feral hemp and it still grows there regardless of our govts many attempts at eradication . While exploring we always left good seeds in the dirt in hopes of a random hybridization lol . As for beans being frozen in the mail , no worries as I usually just place them into my own freezer for long term storage when they arrive like so , or I thaw them out for a day before attempting to germinate .. Peace .PotSnob