iCloud Mail Issue??

Since last night I have not been able to access my iCloud mail. I get the following password;

The iCloud IMAP server “p99-imap.mail.me.com” rejected the password for user “my.name”

Enter your password again or cancel.

This is the case on my iPhone, iPad, Mac, and when trying to access via iCloud.com.

I don't see anything about a problem?? Any ideas? I know my password is correct as it allows me to access my calendar, etc.