We were made aware of Malwarebytes blocking our u.cubeupload.com domain due to some dodgy people uploading viruses disguised as images. These images were hotlinked in spam emails.
The security hole which allowed this to happen has been fixed and we’ve requested our domain to be removed from Malwarebytes’ block list, which they have agreed to do.
In due course we will be going through the catalogue of uploaded images to track down any remaining hack files so we can delete them and ban the uploaders.
Thanks for your patience with this problem, I know it has affected a fair number of our users.