[Dovecot] Disable APOP challenge in POP3 login greeting

[Brad Davidson]

Timo,

It looks like Dovecot 2.0 appends an APOP challenge to the POP3 greeting
even if APOP is not an enabled auth mechanism. Is there any way to
disable this? We don't support APOP, and the challenge includes the
private hostname of the server, which we'd rather not have in the
banner.

It looks like get_apop_challenge in 1.2 returns NULL if APOP isn't
supported, which causes auth_client_ready to omit the banner... but I
see no such check (in fact, no way for get_apop_challenge to return
NULL) in 2.0, even though pop3_client_send_greeting tests for it.

Thanks,

-Brad