A couple of weeks back I sent an email to a professor in a University in my home country with whom I have never known on any personal or professional level. My intention was to seek potential collaborations with him as a recent graduate with a BSc should I return home.
He did replied and to which I responded. One of his question to me was whether I am happy to collaborate without being paid to which I replied, "Yes, I am happy but I am only able to work on any project outside of standard office hours due to foreseeable industry commitment".
Since then, I have not received any replies.
Would it be appropriate for me to ring him up?