Yup. I experimented on a few ways to ship. You can do two day can work. I had mailed some to @Thuan 2 day no issues. I mailed some to our buddy Woody longer, he gotta container of death. You don't have to overnight them though.@Kasrift has shipped me 2 days but it wasnt this freezing cold. During this time, i would go with overnight with heat packs
When I was breeding them, I left them in containers with no circulation or air and as long as they stay warm, they are fine. Reefdude has a YouTube video, he leaves them in closed jars.