[WordPress] An example of how to specify a custom SMTP server when using the wp_mail function.

acme-email-class.php

<?php

class Acme_Email {

	public function __construct()  {
		
		add_action( 'phpmailer_init', array( $this, 'configure_smtp' ) );
		add_filter( 'wp_mail_content_type', create_function( '', 'return "text/html";' ) );
		add_filter( 'wp_mail_from', array( $this, 'from_email' ) );
		add_filter( 'wp_mail_from_name', array( $this, 'from_name' ) );

	}
	
	/**
	 * @param     string    $message    The HTML document to send as the message.
	 */
	public function send( $message ) {
		wp_mail( 'everyone@acme.com', 'Your Weekly Newsletter', $message );
	}

	/**
	 * @return    string    The email address from which the newsletter is being sent.
	 */
	public function from_email() {
	    return 'newsletter@tubular.com';
	}

	/**
	 * @return    string    The name from which the newsletter is being sent.
	 */
	public function from_name() {
	    return "Your Bodacious Newsletter";
	}

	/**
	 * @param    PHPMailer    $phpmailer    A reference to the current instance of PHP Mailer
	 */
	private function configure_smtp( $phpmailer ){

	    $phpmailer->isSMTP();
	    $phpmailer->Host = 'smtp.acme-server.com';
	    $phpmailer->SMTPAuth = TRUE;
	    $phpmailer->Port = 25;
	    $phpmailer->Username = 'server@acme.com';
	    $phpmailer->Password = 'acme-acne';
	    $phpmailer->SMTPSecure = FALSE;

	}
	
}

acme-email-constructor.php

<?php

class Acme_Email {

	public function __construct()  {
		
		add_action( 'phpmailer_init', array( $this, 'configure_smtp' ) );
		add_filter( 'wp_mail_content_type', create_function( '', 'return "text/html";' ) );
		add_filter( 'wp_mail_from', array( $this, 'from_email' ) );
		add_filter( 'wp_mail_from_name', array( $this, 'from_name' ) );

	}
	
}

acme-email-functions.php

<?php

	/**
	 * @return    string    The email address from which the newsletter is being sent.
	 */
	public function from_email() {
	    return 'newsletter@tubular.com';
	}

	/**
	 * @return    string    The name from which the newsletter is being sent.
	 */
	public function from_name() {
	    return "Your Bodacious Newsletter";
	}

	/**
	 * @param    PHPMailer    $phpmailer    A reference to the current instance of PHP Mailer
	 */
	private function configure_smtp( $phpmailer ){

	    $phpmailer->isSMTP();
	    $phpmailer->Host = 'smtp.acme-server.com';
	    $phpmailer->SMTPAuth = TRUE;
	    $phpmailer->Port = 25;
	    $phpmailer->Username = 'server@acme.com';
	    $phpmailer->Password = 'acme-acne';
	    $phpmailer->SMTPSecure = FALSE;

	}

}