not using names

I feel like such a fool. I just applied to a bunch of internships and wanted to get them out as quickly as possible and in my hurry, I completely forgot to actually look up the names of whoever I was emailing and simply addressed them as “Dear [insert name of magazine].” Is this going to reflect really poorly on my part? Could this be seen as overall carelessness? AND I think I made a typo in one of my sentences. I really should proof-read. Ugh.