In addition to ensuring that you use SMTP method in your PHP codes, there are two easy steps that can improve your email delivery drastically.
- Login to your web hosting cPanel by going to http://yourdomain.com/cpanel
- Under Mail, click on “Email Authentication”.
- Enable SPF and DomainKeys respectively.
These two functions essentially help other mail servers to decide that your emails are originating from a real email account.
The above information is relevant to Web Hosting powered by cPanel packages only.