OS: Windows; IceWarp Server Version: 11/10
POP3/IMAP email clients reports problems downloading messages on Windows Vista.
The mail client doesn't receive anything past the RETR command and the session times out after a while.
The solution is described in the following MS KB article:
After applying the fix suggested by the article mentioned above, everything will start to work again.
Important: the netsh command must be run explicitly with administrator privileges, even if the current user already owns them.