QUOTE
We have phased out support for using a percent (%) sign instead of an at sign (@) for login usernames. If you have been using the 'username%spamcop.net' format for logging in to POP or IMAP, please switch to 'username@spamcop.net' or you will have problems connecting.
The percent sign alternative was originally used because buggy old e-mail clients did not support "@" in the username field. Modern clients do not have that problem.
