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.
I happen to know of at least one (partial) client implementation (I happen to have written which is used by an iPhone application for POP3 user credential verification) which actually interprets IN-USE as it is defined by the RFC.
What about the reverse? If no IN-USE is sent, how many clients will just treat it as authentication failure and ask the user for the password again, without showing the "internal failure" error at all? (I don't know the answer. I assumed IN-USE would cause less problems.)