How can I prevent emails sent via wordpress wp_mail from being sent to spam?

How can I prevent emails sent via wordpress wp_mail from being sent to spam ?? The company's intranet is based on word & nbsp; press and uses wp_mail to send emails to people in the intranet. The problem is that all emails received in outlook are in spam, ask how to send emails to inbox! (By the way, how does the mail receiving client identify spam? How does one prevent emails sent via wordpress wp_mail from being sent to spam ??
The company uses word press to send emails to people in the Intranet using wp_mail. The problem is that all emails received in outlook are in spam,
Ask how to send emails to inbox!

(By the way, how does the client identify spam ??)
------ Solution --------------------
What is spam?

IT. SOHU. COM