SMTP auth support can be added in WordPress by third-party plugins.
Do the following steps to add SMTP authentication to your WordPress install.
2) Unzip the file to get the file named wp_mail_smtp.php
3) Copy the file to the plugins folder (\wordpress\wp-content\plugins)
4) log in to WordPress as admin and click on plugins. You can see WP-Mail-SMTP and activate it.
5) Click on 'options'-> Email to Modify the SMTP settings and change the resulting settings.
>Specify the 'from name' and 'email address' created under your domain.
>Choose to send mail by SMTP
>Name an SMTP host (mail.domainname).
>Choose to use SMTP authentication or not.
>Enter an SMTP username and password. Once you finish. Press on "update" options.
7) Test the mail function from where handling " send Test"