Ask the person you are most likely selling it to.
If shipping to auction this is what FHA recommends on page 7 here:
https://www.furharvesters.com/pdf/pelthandling.pdfDRYING TH E CASTOR GLANDS
Castor glands naturally have a high moisture content. The end
user wants the flesh inside each pod, not the water content. Once
you have removed the castor hang them to dry at 60- 70oF. The
humidity level in your skinning/drying room affects the amount of
drying time needed to properly dry each pod. Humidity levels are
high in the spring months, therefore they will take longer to dry.
The pod should be dry to touch, 7 days minimum with ideal low
humidity conditions.
After 2 days open them up to allow the center to dry between the
castors. After the pod is dried it should be stored in your freezer. As
you get closer to your shipping date the pods will need to be taken
out of the freezer and thawed. The pods will need to be dried again
by either placing them on cardboard and or re-hanging them.
Because castor glands will continue to shrink once your shipment
arrives at our warehouse the company will deduct shrinkage. The
amount deducted for shrinkage will be greater if the shipment is
received in a wet condition caused by the glands not being properly
dried.
Shipping castors
Shipping castors is easy. Just place in an onion bag or paper bag
and include it with your fur shipment. Larger shipments should be
shipped in a cardboard box. Place in the bottom of your fur bag. It
is a good idea to use a paper bag even if you have them in an onion
bag. NEVER SHIP CASTOR IN PLASTIC! Castor needs to
breathe, Castor shipped in plastic will cause rot. Rotten castor are
not saleable and will be declared no-value and will be disposed of.