Installing Form Mail Script Question

It seems no matter the server IP customers are unable to write PHP scripts that will make it through to Gmail, Yahoo, and other free email services. I wanted to try Swift Mailer but can't seem to find a download Zip, RAR, GZ, tar or any other format. Every Google request just takes me to a page showing a conversation that isn't actually anything. A URL would be wonderful. I don't know what it is about cpanel and sent OS 7.4 with PHP 7.2 but messages sent to Gmail especially are not received. Let's see if swiftmailer can solve the problem.