I'm trying to use Joomla's Mass Mail function to test emails being sent from Joomla and a contact form plugin (Fox Contact). When trying to send an email using the Mass Mail form, Joomla shows the error
The following from address failed: email@example.com (firstname.lastname@example.org is the SMTP username and from address).
I have confirmed the SMTP details are correct in Site > Global Configuration > Server Configuration > Mail Settings I have also tested the configuration using a telnet connection from the web server, which is able to send emails after authenticating using the username and password in Joomla.
I then tried to enable SMTP debugging by editing
~/libraries/phpmailer/phpmailer.php and changing
false to 2. However this does not show any additional output (other than the above
address failed message).
How can I fix the SMTP sending, or enable debugging to find the cause of the issue?