This policy setting allows you to specify if the user is able to use IMAP4 and POP3 e-mail accounts. Note that this policy ...

"This policy setting allows you to specify if the user is able to use IMAP4 and POP3 e-mail accounts.  Note that this policy setting affects only the Microsoft e-mail application. To prevent users from accessing IMAP4 or POP3 e-mail accounts using a third party application, you must restrict application execution by configuring the Application Disable policies or by configuring Security Policies to allow only those applications that are signed by trusted authorities to run.  If you enable this policy setting, then any e-mail accounts that use IMAP4 or POP3 protocols are turned off. The user is not able to synchronize any existing IMAP4 or POP3 e-mail accounts with the corresponding e-mail servers, and the user is not able to set up a new IMAP4 or POP3 e-mail account. The user may be able to view existing e-mail messages for IMAP4 or POP3 e-mail accounts if the messages were downloaded to the device before the policy setting was changed. The ability to provision a new IMAP4 or POP3 e-mail account via Email2CSP is still allowed, but if a new Internet e-mail account is created via Email2CSP after this policy setting is enabled, the user will not be able to synchronize that e-mail account with its e-mail server.  If you disable or do not configure this policy setting, then the user is able to use IMAP4 or POP3 e-mail accounts."