If it's only 20 students, maybe just ask them to come by your office during office hours. Most of my professors would just post grades in the hallway using stud

If it's only 20 students, maybe just ask them to come by your office during office hours. Most of my professors would just post grades in the hallway using student IDs, but a few did it this way. It gives you a chance to connect with the students and give some personal feedback. At the graduate level this can be helpful not only for them, but also for you since these students are people you will likely work with later in industry and academia. If you are not in your office much, then I would just offer the GPG option. Sending 20 e-mails will not take very long. Out of the 20 students, I bet only half of them get their act together and e-mail you a key, so it's really more like 10 emails that you would need to send.