imap

Creating an in house signing [aka CA] certificate is a common practice; this allows you to generate free cerficates for internal use. For Windows hosts distributing this CA certificate to all the clients and relevant servers can be accomplished using Active Directory GPOs. Certificate management on LINUX hosts on the other hand has always been a swamp of tedium where the certificates often need to be configured into each client or service. Recent distributions have eased this process considerably by including a quasi-standardized set of scripts and certificate store locations.

An interesting thread has occurred on the Cyrus IMAPd mailing list regarding the lowly ampersand. Apparently in the encoding used by IMAP (a "modified UTF-7 encoding") the ampersand ("&") requires escaping. So it works fine to have subfolders whose name contains an ampersand as IMAP clients, of course, use the appropriate IMAP encoding.