This is an old revision of the document!
If you receive a 'POP3 Client Error' something like:
-ERR Password supplied for “xx” is incorrect
this means that the password on the 'In Mail' tab in VPOP3 for the indicated user is entered incorrectly.
Check with the ISP that you have the username and password correct, and ensure that you have entered the username and password using the correct case letters.