Using PHP mail function leads to slow order confirmation

[patrmich]

Hello,

I am facing the following problem (for a shop built with Prestashop 1.5.6.2)

1- Using Advanced settings > Emails > Use PHP mail function

Sending the test email takes 3 or 4 seconds.

The order confirmation takes more than 30 seconds or more (that, of course is not acceptable for the customer)

In this case :
The customer receives properly the order confirmation mail (order_conf.html)
The merchant receives properly the order confirmation mail (through mailalerts.php)

2- Using Advanced settings > Emails > Set my own SMTP parameters
Sending the test email takes less than 1 second.
The order confirmation takes 2 or 3 seconds only (that is convenient for the customer)

In this case :
The customer receives properly the order confirmation mail (order_conf.html)
But the merchant receives, only from time to time, the order confirmation mail (through mailalerts.php)

3- Of course, I got in touch with my web hosting, but until now, he was unable to solve the matter.
His recommendation is to use the PHP mail function, but that leads to an unacceptable order confirmation time.

Would you have any idea of the way to fix the trouble ?

I thank you in advance for any help.

Patrick