When using this plugin with the WP-DB-Backup plugin which emails me a daily database backup, it returns the following error (within a hidden frame):
Fatal error: Cannot redeclare class smtp in /var/www/html/wp-includes/class-smtp.php on line 25
I can resolve this by simply renaming your class SMTP to SMTP1 in the XPM4/SMTP.php file as well as altering the class_exists('SMTP') to SMTP1 in XPM4/MAIL.php
This resolves the conflict and allows me to use your plugin for receiving automated backups of my sites database. I'd love it if you could resolve this in your code as well since it is directly conflicting a class already defined within WordPress.
Otherwise this plugin works beautifully, thanks!