I'm a undergrad, and I had an interview with an institute within my university. I received this email from my interviewer about a week after the interview itself:
I would like to thank you for taking the time to interview with me on Monday. Due to our space constraints, we were only able to accept one intern for the spring semester, and that position has been filled. However, because we feel that you are a very qualified candidate, we would like to know if you have any interest in or availability for the summer 2016, fall 2016, or spring 2017 terms. If you do, please let me know, and we will hold a space for you for one of those semesters.
You don't have to let me know right now. I will keep your materials on file; just contact me when you know what your availability might be for the other semesters.
Thank you again for coming in for an interview, and I wish you the best of luck in your continued studies.
What I'm wondering is exactly how I should respond over email. I'd be interested in the position for either the summer and/or fall terms, but I'm not sure how concrete this offer is, and how exactly I should contact them once those terms roll around (i.e. should I email them my class schedule or ask them to what hours they'd like me to work and schedule my classes around them). Any tips on how to format my response? Should I approach the issue as though the internship is guaranteed for whatever semester I choose, or would that be too presumptuous?