Originally published at: http://www.sitepoint.com/reliable-wordpress-email-external-smtp-integration/
As a webmaster you probably find yourself scrambling to complete various tasks to keep your site functional. While it’s easy to focus on visual items such as the design or enabling key functionality, many WordPress owners make the mistake of not connecting their sites to an SMTP server. Whether you’re intimidated by the thought of customizing your site or just haven’t thought of this aspect, SMTP can be integrated with ease through off the shelf plugins.
The Built in WordPress Mail Function
By default, WordPress comes with a built in mail function known as wp_mail. This is a wrapper for PHP’s mail() function which typically uses Sendmail for sending emails.
Unless you edit the wp_mail function, as discussed on the WordPress Codex, the default subject line for your messages will be “WordPress” and the default sender email address will be wordpress@yoursite.com.
Unfortunately on many WordPress websites, using the default mail server doesn’t work due to hosting restrictions (due to spam controls) or conflicts with other plugins. If you have a security plugin for example, those are known to be a major culprit of this function not working.
Rather than trying to troubleshoot wp_mail() issues or having the default mail server stop working without your knowledge, it’s best to avoid using the wp_mail() function as much as possible.