Email do not correctly interpret variables in relevant template

Hi,
I’ve recently installed SuiteCRM 7.10.22 LTS on a LAMP environment
Linux 18.10 Kernel 4.15.0.70
Apache 2.4.29-1 Ubuntu 4.11
MySQL 5.7.25
PhP 7.2
I’ve tryed to use several predefined templates but all the mail has the varibles not interpreted and therefore displayed in plain text as $variable, even if the
Send in Plain Text check box is not thicked
I’ve also tried to create a new template, using some other variable relevant to the employee I’m using, but with the same results
For the System-generated password email template i got the mail in plain text
Here is your account username and temporary password:

Username : $contact_user_user_name

Password : $contact_user_user_hash

$config_site_url

After you log in using the above password, you may be required to reset the password to one of your own choice.

Any word of advice?
Thanks