I signed up with the same email about a year ago i think, and when trying to make an alt account, the page says you aren't allowed to sign up using the *.programmer.net domain.

ClassiCube only supports a couple of email providers, you can always request the admins to add support for more.

oh, thanks!

Hey guys,

I just saw this thread from 2019 which fits to my issue:
Where can I request admins to add support for our e-mail provider?

Thankful for any help.