Why are my emails being sent as spam?

When using my yahoo email, I noticed I wasn't getting any responses to my emails. I emailed another yahoo email account I have and it showed up in spam folder. It is a new email account I just created for my business and am wondering if since it is new it spams everything I send for a while. I also tried using a company logo on signature but thought that may be the reason for emails going to spam, so I disabled signature totally, and they are still sent to spam. Why?