Timo Sirainen <tss@iki.fi> writes:
On Sun, 2010-03-28 at 23:09 +0200, Rainer Weikusat wrote:
RFC2449 defines the IN-USE extended POP3 response code as
8.1.2. The IN-USE response code
This occurs on an -ERR response to an AUTH, APOP, or PASS command. It indicates the authentication was successful, but the user's maildrop is currently in use (probably by another POP3 client). http://www.faqs.org/rfcs/rfc2449.html
In contrast to this, the POP3 login code in client_authenticate.c will send IN-USE whenever authentication was not successful because of some kind of internal failure[*].
Yes. In both cases the failure is temporary.
The RFC excerpt above states that "It indicates the authentication was successful but the users' maildrop is currently in use". The difference arguably doesn't matter much for the intended purpose of the response code, namely, provide a more reliably way to check for 'mailbox locked' states than trying to analyze the 'user message' part of the string, it just means that IN-USE does not communicate anything about the validity of the credentials which were being used.