As someone who has been in the industry for 5 years, I have accumulated a wealth of knowledge and expertise that makes me the perfect fit for your Symfony 6 project. Not only am I extensively proficient in HTML, MySQL, and PHP, but I have a deep-rooted understanding of Symfony PHP which is key to implementing the requirements you've specified.
In addition to my technical abilities, I prioritize excellent client communication and satisfaction. Precise documentation is one of my key strengths, meaning you can count on thorough notes on the libraries installed, configurations made, files configured, and how to modify the sender's mail.
Lastly, your need for a functional demo to showcase the system’s capabilities is important and very much doable. I can complete this on top of integrating your Symfony 6 with your desired SMTP server for smooth email functionalities and sending notifications/news to registered users. At a budget of $20, you won’t find a better offer for my level of skills and dedication anywhere else. Let’s make this happen!