This is what comes up in my logs/imap:
[24-Apr-2010 14:46:34 -0400]: S: * OK [CAPABILITY IMAP4rev1 UIDPLUS CHILDREN NAMESPACE THREAD=ORDEREDSUBJECT THREAD=REFERENCES SORT QUOTA IDLE ACL ACL2=UNION] Courier-IMAP ready. Copyright 1998-2008 Double Precision, Inc. See COPYING for distribution information.
[24-Apr-2010 14:46:34 -0400]: C: cp01 CAPABILITY
[24-Apr-2010 14:46:34 -0400]: S: * CAPABILITY IMAP4rev1 UIDPLUS CHILDREN NAMESPACE THREAD=ORDEREDSUBJECT THREAD=REFERENCES SORT QUOTA IDLE ACL ACL2=UNION
[24-Apr-2010 14:46:34 -0400]: S: cp01 OK CAPABILITY completed
[24-Apr-2010 14:46:34 -0400]: C: a001 LOGIN "user@domain.com" "password"
[24-Apr-2010 14:46:34 -0400]: S: * BYE Temporary problem, please try again later