Awe Geez, this dummy just misread the question (again)
I've only freeze-thawed one pollen for use later that season, then refroze and used the same pollen again the second year with good results on compatible partners. I used it again after that, too but it failed and I blamed incompatibility. But this is based on a single test tube of pollen from one diploid Trumpet only. So beware.
I do know for sure that unfrozen pollen can be shipped world wide from Point A and refrozen at destination Point B, then thawed and used successfully. I would suppose shipping frozen pollen intended for use soon after arrival would be ok as well. I don't think it would matter too much what season it is.