I am just finishing up an MSc degree in Canada and am looking to begin sending inquiry emails to potential supervisors regarding available PhD positions (also in Canada). However, I am unsure how to approach one specific scenario:
I am looking to email a potential supervisor who I have worked with in the past although not very closely as he has never been a direct supervisor and is at a different university. However, he still knows most of the pertinent information that I would typically include in an inquiry email (e.g. current school/program, research topic, GPA, etc.). He also knows that I am aware of his current research and his recent publications as my research is closely related and we have completed fieldwork together that is related to both of our topics.
I am unsure of how formal to be or what to include in my email given that we do have somewhat of a pre-existing relationship. Typically I would try to speak in person with anyone that I already know but given that he is at a different university that wouldn't be possible without advance planning.
Any guidance on what to include in an email asking about potential PhD openings and hopefully arranging a meeting to discuss any opportunities in person would be much appreciated!