[SpamCop-List] Cannot log into IMAP mailserver as @spamcop.net ????!!!

[A. Flottwell]

this is probably a stupid question, but I get this everytime I want to 
check my held mail!
No more reports, mailbox probably overflowing - ok I can still empty the 
stuff from webmail.
But what has happened?

I can access my mail account from anywhere, but  *NOT* from the held 
mail link!

Please give me a HINT
a.