This is a very interesting question: I had envisaged users rebranding the application and modifying its functionality to suit their needs and those of their clients, but I hadn't thought about redistribution...
You are welcome to redistribute the free version, with the following conditions:
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1) I would expect to be credited as the original author, with a link to my website in the documentation
2) I can only support the build of simpleContact Lite that I distribute through my website - I do not support any modifications to the application or its documentation in a redistributed build
3) If you do not want to assume the role of supporting users of a modified build, I would prefer that you either a) distributed an identical copy of the build on my website or b) didn't redistribute the application at all and linked to my website instead
4) If you modify the application please use the instructions on this forum to disable the version check and sever any links to my documentation where it is made incorrect by your changes
5) PHPMailer is the only third-party library linked to Lite. You need to supply the PHPMailer files with it and abide by the terms of the license under which it is released. If you want to supply the very latest version you can download it from Codeworx Technologies
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If your main reason for redistributing the application is that you feel the present documentation leaves something to be desired, I would gladly accept your feedback on how it can be improved.