Evolution to Exchange/ ISA in the middle

Hi, I have been using Evolution to Exchange for years with minimum problems. Recently, the Exchange 2003 OWA was put behind an ISA server. I can login to OWA from Firefox no problem but I can’t get Evolution to log in. Any ideas?

Can you make sure the proxy function has been enabled of ISA server.
If the answer is yes, please check proxy setting of evolution first.