I think I found a workaround to satisfy this question. I couldn't get @kindall 's answer to work for some reason. So I'm using this:

emails = [email[:email.find('@')] for email in user_emails] # return everything up to the @

This will return everything up to the @ symbol. If you want everything after the @ symbol, run the following:

emails = [email[email.find('@'):] for email in user_emails # returns everything after the @ symbol