Source still reads "PHP Version 5.5"

[XericDesign]

All the source files still indicate PHP Version 5.5 despite this being 6.7.

[Synchro]

No, it's referring to PHP 5.5, not PHPMailer. That specific text is an old phpdoc convention (which still applies because PHPMailer 6.7 still runs on PHP 5.5) for indicating the supported PHP version that predates composer.

[XericDesign]

Ah - thank you.