I have responded on GitHub, https://github.com/gajus/usus/issues/14#issuecomment-314443224.
I am sorry to have inconvenienced you.
The email has been sent to a hand curated group of people matching a very specific targeting criteria. It is not an en masse email. Email was sent from my personal email address; I took care to reply to every email and offered help to those who expressed interest in usus.
Email has resulted in a dozen of conversations suggesting new features and feedback from users familiar with the pre-rendering issue. My sole intent is to create a strong community by encouraging participation and personal contact with the project authors. After all, this is what open-source is — a community.
I personally apologies to you and others whom I have inconvenienced.
If you have suggestions how to approach email communication better in the future, please advice. Furthermore, no one will receive a second email from me about this or future projects unless explicitly asked in response to the original email.