[Dovecot] When imapc can't connect to remote IMAP prevents user login (and blocks LDA)

[Marcin Mirosław]

W dniu 2012-12-18 21:33, Timo Sirainen pisze:
Hi Timo, hi all!
> On Sat, 2012-12-15 at 18:14 +0100, Marcin Mirosław wrote:
>> I'm using dovecot 2.1.12-r1.
>> When remote imap server rejects connections then I can't login into
>> account and MTA can't deliver emails to maildir also.
>>
>> I'm attaching snippets of logs:
>> 2012-12-15T18:05:43.072594+01:00 meteor dovecot: imap-login: Login:
>> user=<marcin at mejor.pl>, method=PLAIN,
>> rip=2001:470:1f0b:1ab3:50af:bef4:6918:78ad, lip=2001:470:1f15:1b61::2,
>> mpid=32533, TLS, session=<T0GGKOfQCQAgAQRwHwsas1CvvvRpGHit>
>> 2012-12-15T18:05:43.442598+01:00 meteor dovecot: imap(marcin at mejor.pl)
>> <T0GGKOfQCQAgAQRwHwsas1CvvvRpGHit>: Error: imapc(imap.wp.pl:143): Server
>> disconnected: Connection reset by peer
>> 2012-12-15T18:05:43.442598+01:00 meteor dovecot: imap(marcin at mejor.pl)
>> <T0GGKOfQCQAgAQRwHwsas1CvvvRpGHit>: Error: imapc(imap.wp.pl:143):
>> Authentication failed: Disconnected from server
>> 2012-12-15T18:05:43.442598+01:00 meteor dovecot: imap(marcin at mejor.pl)
>> <T0GGKOfQCQAgAQRwHwsas1CvvvRpGHit>: Error: imapc: Command failed:
>> Disconnected from server
>> 2012-12-15T18:05:43.442598+01:00 meteor dovecot: imap(marcin at mejor.pl)
>> <T0GGKOfQCQAgAQRwHwsas1CvvvRpGHit>: Error: user marcin at mejor.pl:
>> Initialization failed: Namespace 'xxx-wp-pl.': imapc: LIST failed:
>> Internal error occurred. Refer to server log for more information.
>> [2012-12-15 18:05:43]
>> 2012-12-15T18:05:43.442598+01:00 meteor dovecot: imap(marcin at mejor.pl)
>> <T0GGKOfQCQAgAQRwHwsas1CvvvRpGHit>: Error: Invalid user settings. Refer
>> to server log for more information.
> 
> Would be nice to have fewer and nicer error message lines of course.

This isn't problem for me.

>> I'd like to ask is this behavior correct?
> 
> You're using Dovecot as simple imapc proxy without local mails? Then
> yeah, what else could it really do?

Here is problem, I'm using local mails also!:) So when remote imap
server doesn't want to talk with me I can't even check mail emails.
I can understand this behavior (e.g. lda can't deliver email because
sieve script could put such email in folder available via imapc) but it
looks like a kind of DoS for my mailbox;) Maybe some kind of switch
could be implemented: treat imapc errors as critical or not? Just an idea.
Thanks,
Marcin