This article assumes that you already have PHP installed and working and your PHP location is C:\PHP

• Download go-pear.phar file from https://pear.php.net/go-pear.phar and save it as C:\PHP\PEAR\go-pear.phar 
• Open command prompt, navigate (cd) to C:\PHP\PEAR and run: php go-pear.phar
• Accept all installation defaults:
  1. Install Type: System-Wide
  2. Default paths: Yes (double check that path to your PHP install is correct)
  3. Update php.ini: Yes
     
     
• Add ;C:\PHP\PEAR to Windows Environment PATH Variable: Control Panel > System > Advanced System Settings > Environment Variables > System Variables > Path
  
  
• Make sure PEAR is working from the command prompt: pear version should return something like this:
  
• Install PEAR Mail and Net_SMTP packages by running following commands:
  • pear install Mail
  • pear install Net_SMTP
    
• If you intend to use SSL/TLS enabled SMTP servers, enable openssl PHP extension:
  • Open php.ini and uncomment following line: extension=php_openssl.dll
  • Restart IIS: open command prompt and run iisreset

May 2017
Windows Server 2008R
Internet Information Services 7 (IIS7)
PHP 7.1.5
PEAR 1.10.4