Php mail script upgrade

Where is the script?

The php file is attached

But I could not get it to work on Ubuntu 18.04 or Debian 9

Is there any error message or any output? We need to know what you mean by could not get it to work.

Do you get any output from echo statements?

Can you take a practical test? Do you have any 18.04 ubuntu server or debian 9 server?

Unfortunately, I don't have anyone from them that why I'm trying to know from you what happens exactly when you execute the PHP script.

Have you considered migrating the script to use PHPMailer (https://github.com/PHPMailer/PHPMailer)

It takes a lot of the hassle out of sending emails from PHP.

What SMTP email server (like Postfix) is installed on the other systems?  You can't send email without a SMTP server.

The interesting thing is to make it work in other distros just like it works on ubuntu 14.04. The idea is to make the script work on Ubuntu 18.04 as well. Works on ubuntu 14.04 with Postfix

SMTP servers which are required for the PHP mail() function to work are NOT automatically installed on the LInux systems I have.  I had to do the install myself.

In the description I explained that it is installed and works on ubuntu 14.04, the point is that even with everything installed and configured correctly it does not work in the most current versions of ubuntu (16.04, 18.04)

Then you need to debug your code to know where exactly the script stops, it does not work doesn't help us so much to identify the problem source, share with us the output of your script, screenshots, anything could help us to help you...

the problem is that it does not generate any error or log message

SMTP program requirements.
http://php.net/manual/en/mail.requirements.php

mail() configuration.
http://php.net/manual/en/mail.configuration.php

And according to this page http://php.net/manual/en/function.mail.php , your code does not have a 'message body' or content.

Dave Baldwin It works fine on Ubuntu 14.04 with postfix and php5

Dave Baldwin It works fine on Ubuntu 14.04 with postfix and php5

 You have already said that.  But you seem to be ignoring my comment that Postfix or Sendmail are NOT installed by default... but are Required by the PHP mail() function.  The Ubuntu and CentOS installations that I have did NOT have a SMTP server installed until I installed it.

dave gave the proper indications :
the mail php function relies on the system's sendmail command.

- this requires to be configured in php. check with phpinfo
- this requires the sendmail command to exist on the system. if postfix is installed, it does. be careful : you might be running in an fpm chrrot
- this requires the local MTA to be running and pickup to be configured properly. this should be the case with a postfix default install.

the php config can be checked with phpinfo and be enabling error output : the mail function will throw an error if it is unhappy.

the mail config can be tested by sending a mail from the command line using the mail command.
also try to tail /var/log/maillog or mail.log whichever exist