I am not sure if this being caused by my company's access policies (which are severe i.e. no webmail access), or by Plusnet's servers, but I've been able to use the old webmail service at work with no problem (probably because it uses a secure access). But since Plusnet temporarily suspended the webmail service the other day I got the message below.
You were denied access because:
Access denied by access control list.
Today this is the same message I get when I try to access the beta webmail service. However the button to use the old service now works OK. This is the only way I can send private mail from work, it would be sad to lose it.