[Dovecot] Re: Small change to make dovecot pop3 uw-imapmigrationfriendly

Brian Candler B.Candler at pobox.com
Fri May 28 16:14:54 EEST 2004

On Fri, May 28, 2004 at 04:32:22PM +0400, Oleg I. Vdovikin wrote:
> > i.e. changing the format string does not change the UIDs of existing
> > messages; or put another way, the format string is only applied the first
> > time that a new message is seen.
>     IMAP UID is just a number. And it's appearence is fixed. It's not an
> UIDL response. Right?

I'm sorry - given the discussion about its *format* being important, I was
assuming we were talking about POP3 UIDL.

IMAP UIDs are *defined* to be monotonically increasing integers, and number
1234 is 1234. (RFC3501 is bad, but it doesn't say you can send them in hex

>     Just to clarify: there is no importing at all. Dovecot stores UID and
> UIDVALIDITY internally and basically it's compatible with uw-imap. But the
> UIDL command answers via POP3 is different. So, I need to be able specify
> formatting string for the UIDL answer.

Ah OK. But POP3 servers are not *required* to use any particular format for
UIDL. So when importing messages from server X, then the UID could be any
arbitary string. If you want to allow transparent migration of messages from
server X to dovecot, then you need to import the UID string as-is.

Maybe some POP3 servers derive their UIDL from the IMAP UID, but not all do
(courier-imap for one; also any standalone POP3 server which does not have
an IMAP component)

> This does not requires any changes
> for old messages and for the new ones. I'm just want sit fixed at %08x%08x
> format forever and do not want to switch to %u.%u used by dovecot...

The other point is that if you have a global default like this, and one day
you decide to change from one format to the other, then all POP3 clients
will suddenly believe that all the stored mail is new and will download it



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