Mishnah:
Garments may be sent on Yom Tov, whether they’re sewn up or not, even if they’re shaatnez, provided they’re sent for the purpose of Yom Tov. But a spiked sandal cannot be sent [there was a special Takanah made by Chazal that spiked shoes may not be worn on a day when Jews get together due to an unfortunate stampede that once happened while Jews were hiding in a cave], nor a shoe that is not sewn together.
Rabbi Yehuda: Nor a white [undyed] shoe which needs a craftsman to complete it.
This is the rule: Anything that can be used on Yom Tov, may be sent.
Gemara:
Challenge: Unsewn clothes can be used as blankets, but what use can one have of shaatnez?
Would you suggest it be folded under to be used as a cushion?
We learned a Beraisa: “It [shaatnez] should not go on you”, but you may spread it out beneath you, but the Chachomim forbade it, lest one thread rise up above his flesh.
Would you suggest that something can be placed to intervene between your body and the shaatnez cushion? But:
Rabbi Shimon ben Pazi quoting Rabbi Yehoshua ben Levi quoting Rabbi Yosi ben Shaul quoting Rebbi in the name of the holy gathering of Chachomim in Yerushalayim: Even if there are ten sheets one one top of the other and shaatnez is beneath them, it is still forbidden to sleep on them.
Resolution: The shaatznez may be used as a curtain.
Challenge: Ulla: Why is a curtain capable of contracting tumah [after all, it’s not a garment]? Because the servant sometimes warms himself with it. [If that’s the case, it should be considered a garment?]