[Dovecot] Effects of going read-only on dovecot & pop/imap clients

[Timo Sirainen]

On Thu, 2009-02-19 at 17:10 +0000, Mark Zealey wrote:
> > Are you talking about only POP3 clients? I suppose in theory it should
> > be possible, but it's such a special case that I'm not going to bother
> > making Dovecot support that. Dovecot really wants to create
> > dovecot-uidlist files. But I suppose you could just have it 
> > create them
> > to some temp directories:
> > 
> > mail_location = maildir:~/Maildir:CONTROL=/tmp/%u:INDEX=MEMORY
> 
> Both IMAP and pop3 - I got the same errors with imap, but thanks to the
> CONTROL= parameter that's fixed now.

With IMAP that's a really bad idea, because then the UIDs won't be
permanent.

> 2009-02-19T16:48:14+00:00 mail2 dovecot: POP3(test2 at markandruth.co.uk):
> Disconnected: Mailbox is in inconsistent state. bytes=0/56, top=0/0,
> retr=0/0, del=0/0, size=0
> 2009-02-19T16:48:14+00:00 mail2 dovecot: POP3(test2 at markandruth.co.uk):
> Couldn't init INBOX: Mailbox was deleted under us
> 
> But second login is fine - must be something to do with the CONTROL
> param.

Probably, yes.. Although didn't it log an error message to error log
(may be in a different log)?

> > And be sure to use:
> > 
> > pop3_uidl_format = %f
> 
> Out of interest, why do we have to use that uidl format, or are you just
> saying we have to use some uidl format? We migrated from courier and so
> use "UID%u-%v".

Because the UIDs aren't permanent with that CONTROL change.

> Hmm, weirdly enough (or perhaps not) dovecot looks successful if I
> delete the message (chmod -r):
> 
> dele 1
> +OK Marked to be deleted.
> quit
> +OK Logging out, messages deleted.

chmod -r? Or -w? Did you do it to the messages or the cur directory? The
only important thing is if cur directory has +w permission.

> Do you think IMAP clients would handle the read-only situation better?

Yes. For example dovecot.org offers read-only mailing list archives.

> I
> can see that it correctly reports the mailbox as read-only if we chmod
> -r files, however if the filesystem itself is mounted read-only, dovecot
> reports the mailbox as being read-write (dovecot 1.1.6)

Dovecot uses access(Maildir/cur) to see if it has write permissions. I
guess the kernel says that the user does. I'm not sure if there's a good
and easy way to fix that.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 197 bytes
Desc: This is a digitally signed message part
Url : http://dovecot.org/pipermail/dovecot/attachments/20090219/5fba4298/attachment.bin