All@broadcast.companyname.co.uk - 404: Remote Server Not Found

Our server is up and running and has the broadcast plugin enabled with default service name. I’ve added all@broadcast.companyname.co.uk and groupname@companyname.co.uk but they show with status “404: Remote server not found”.

Is this to do with having dots in the server name? I wanted to keep them like that so that when people are adding other people they can just add them using their email address.