and, as an addendum to Dean Brown's comment, that also means you must have SSL and you must have IIS enabled on the server.
SSL requires IIS, so you cannot use the SmarterMail web server.
Phonr: (773) 491-9019
Phone: (224) 444-0169
E-Mail and DNS Security Specialist
Network Security Specialist
Customer Service Portal: https://portal.chicagonettech.com
Security Blog: http://networkbastion.blogspot.com/
Web and E-Mail Hosting, E-Mail Security and Consulting