I use Microsoft Outlook check e-mail, reply as:
Error report (0x8004210E)
ERR [IN-USE] internal login failure. Refer to server log for more information.
I use UebiMiau webmail, reply as:
Login Error
Login Error - You cannot Login with the Username and Password Entered.
Please check the Username and Password and try again.
I use SquirrelMail, reply as:
ERROR: Connection dropped by IMAP server.