Download the current version (i.e. http://pkp.sfu.ca/cvs/cvsweb.cgi/ojs2/classes/mail/SMTPMailer.inc.php?rev=1.4
) to your server and replace the existing classes/mail/SMTPMailer.inc.php with this new version.
The new version uses PHP's error_log facility (see http://www.php.net/manual/en/function.error-log.php
) to record debugging information if an error occurs. Typically, it'll be recorded to your web server's log file. Try sending an email with the new file in place and see if any debugging messages are available.
Open Journal Systems Team
Don't miss the First International PKP Scholarly Publishing Conference
July 11 - 13, 2007, Vancouver, BC, Canada