Why does my sent emails go to spam folders?

That's not much information. Do you mean they're going to YOUR Spam folder, or do you mean they go to the spam folders of the people you're emailing? I've never heard of our own emails going to our spam folders, so I couldn't help you there. But if the issue is that the emails you send are going into the recipients spam folders, if they are friends, suggest that they put your email address in their Address Book/Contacts. That would generally resolve that problem.