One of the big reasons that your emails go to spam is that maybe you were previously engaged in spamming activities or you are using shared hosting. The major drawback of using shared hosting is if someone is involved in malicious activities like sending bulk emails, or promoting illegal brands then it is very obvious that every user hosted under that hosting gets involved. So if even one customer sends spam, it could affect your reputation as well. Hence the IP used for raising such kinds of spam activities will also affect you in the same manner. This is why Google often puts the mails sent from webmail into spam.
How to prevent my mail from going into spam? [Updated May 2019]
Although there is no permanent solution to this still you can prevent this from happening by using premium mailing services from GoogleSuite, and ZohoMail.
Hope this answer helped you.. for more queries and suggestions feel free to write or you can also comment below…