dovecot - Sep 2008 - cyrus2courier or cyrus2maildir.py, which to choose?

What's the best utility to use to convert mail folders from a cyrus
2.2.13-10, on a debian 4.0 Etch system, to folders that can be used by
dovecot? 

The http://wiki.dovecot.org/Migration/Cyrus page isn't too clear on
what's the difference.

cyrus2courier says "It should be able to preserve message UIDs, flags
and 26 first keywords."

cyrus2maildir.py says "preserves delivery timestamps and \Seen flags."

But does that means that what cyrus2maildir.py preserves is in addition
to what cyrus2courier preserves?  Or is what cyrus2maildir preserves a
subset of what cyrus2courier preserves?

Thanx!


- Steinar

On Sat, 2008-09-06 at 16:25 +0200, Steinar Bang wrote:
> What's the best utility to use to convert mail folders from a cyrus
> 2.2.13-10, on a debian 4.0 Etch system, to folders that can be used by
> dovecot? 
> 
> The http://wiki.dovecot.org/Migration/Cyrus page isn't too clear on
> what's the difference.
> 
> cyrus2courier says "It should be able to preserve message UIDs, flags
> and 26 first keywords."
> 
> cyrus2maildir.py says "preserves delivery timestamps and \Seen
flags."
> 
> But does that means that what cyrus2maildir.py preserves is in addition
> to what cyrus2courier preserves?  Or is what cyrus2maildir preserves a
> subset of what cyrus2courier preserves?
cyrus2courier does everything, but it requires a supported Cyrus
version.

I think cyrus2maildir.py was written during the time when cyrus2courier
hadn't yet been updated to newer Cyrus versions. It doesn't preserve any
flags other than \Seen.

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>>>>> Timo Sirainen <tss at iki.fi>:
> cyrus2courier does everything, but it requires a supported Cyrus
> version.
Right.  I tried that one first, but I wasn't able to figure out what
arguments to give it.  Eg. what to tell it the courierdir was, and what
the mailbox should be named.

Eg. if my INBOX is /var/spool/cyrus/mail/s/user/sb/ what should the
mailbox argument be? "sb"?
> I think cyrus2maildir.py was written during the time when cyrus2courier
> hadn't yet been updated to newer Cyrus versions. It doesn't
preserve any
> flags other than \Seen.
Ok.  But the arguments are easier to figure out.

However my primary IMAP MUA is Gnus, which stores a lot of the state on
the server as custom flags.  So my best bet may be to use imapsync,
which is said to preserve all flags.

This means two things:
 - The dovecot server will have to appear to Gnus as a new nnimap server
   (that's the simplest and safest), because of changed UIDs.  The only
   state information in theory is lost that way by Gnus, is the cached
   article information.
   However it may be confused if new articles start arriving with what
   it determines to be a lower article number (Gnus translates
   everything into NNTP terms at some point), so it's safest to make
   this look like a new IMAP server to Gnus
 - The dovecot server and cyrus have to be running on the machine at the
   same time.  I have some archive folders with over 30k articles.  I'm
   unsure of the performance of my poor old Pentium II 233, with 128MB
   of memory at that point (it would be cheaper to just move the files)

But anyway imapsync looks safest, so I'll try that first.

Thanx!