Yesterday I received a delivery from a mail-order Homebrew shop I use. However, the package was delivered during the day, and I didn't get home until suppertime. The temperature here yesterday was -13° F. When I opened the box, the vial of White Labs yeast (WL007 Dry English Ale) was frozen solid. I put it in my refrigerator to slowly thaw it back out.
My question is: Will having been frozen dramatically adversely affect the yeast's viability? Of course I'll still do a starter anyway, but how well do yeast typically survive being frozen in the vial like this?