TOPIC: Notice: Could not instantiate mail function.

Hi. I have the latest Joomla! 3.4.8 and iPrice calculator light version com_ipricecalc_1.1.17.
Everything works pretty well, BUT when finalizing the order, I get the error message:
"Notice: Could not instantiate mail function."
Underneath is the "successful sent" message and the email is delivered to the person who ordered.
I'm using the php mailer and my email address is on my domain, the same for super user and global configuration.
Can you help? Thanks.

Check you mail function in Joomla. Create a standard Joomla contact and try to send a message.

My regular contact form works fine.