Email sent from zoho often get in spam

Email sent from zoho often get in spam

I have a big problem with this. Its so easy to send mail to contacts using macro i zoho crm, but i see that very often my contacts dont get the mail. When i send from gmail this never happen. I thought zoho is sending from my emailadress, so i dont understand this. Can anyone help me with this? Thanks. Knut Pedersen