We are sorry your students are having issues creating accounts. We have tested and verified that the Online Challenges system is sending the emails as it should, so our internal system is working properly. The name displayed on the email is “REC Foundation” and it is being sent from the email address "firstname.lastname@example.org" via our challenges.robotevents.com system. The subject of the email is “Welcome to REC Foundation’s Online Challenges,” and we have verified that they are being sent 100% of the time. We recommend that students check all “junk,” “trash,” and “spam” folders in their account(s).
However, because you have stated that they are indeed checking their clutter/junk folders, then it is likely an external issue of the emails being blocked. If your students are doing this in the classroom, they may be blocked by local network or ISP settings, so please check with your network administrator or IT department to verify. Many schools have strict security settings, which may be preventing the verification email from arriving.
Thanks and good luck!