Prior to v7.7.0 you'd have to modify the "class.phpmailer.php" file of the PHPMailer library (libs/phpmailer) in order to set SMTP settings; but in 7.7.0 we have settings for various Mail Transfer Agents and SMTP settings in the Control Panel at: CP -> Master Settings -> Primary -> Basic Tab -> "Advanced Mail Configuration"

Is your email address from the forums on the same domain as the domain name for your site?

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