My Wordpress emails were being rejected by my ISP's SMTP server. I fixed this by editing wordpress\wp-includes\plugg... in the wp_mail() function, the following line: // Set to use PHP's mail() $phpmailer->IsMail(); Which uses the PHP mail feature, To the following: // Set to use SMTP mail() $phpmailer->IsSMTP(); $phpmailer->Host='localh... This uses my local smtp server, but you can look at the phpmailer class and set variables here to use whatever smtp server you wish, authenticated, ......