Courier-IMAP maibox to cyrus-imap maildir

[Aleksandar Milivojevic]

Simon Matter wrote:
> I don't know imapsync nor mailsync but I think something like rsync just
> for IMAP may be a good solution. You can presync the large amount of data
> sometime before actually migrating the server. Then, before finally
> switching the server, resyncing should be quite fast. Loosing flags is
> really not acceptable in many environments.

Imap-sync can do exactly what you described.  I've tried it out.  Sounds 
good in theory.  Not so good in practice.  It is faster, but it still 
takes a lot of time.  Still too slow for moving very large quantities of 
email.  In my example, two day work would be cut to half a day, maybe 
even an entire day.  And my user base isn't really that large (it is 
just that some of them have huge mailboxes).  Again, there's that small 
password problem (you need to know all your user's passwords or reset them).

Plus, with one IMAP server (wu-imapd to be more specific) imap-sync 
didn't play all that good if the users were allowed to be logged in 
while it was syncing mailboxes.  If the user had folder open from his 
email client, sometimes imap-sync wasn't able to read flags on some of 
the messages.  Not sure if it was bug in imap-sync, Perl IMAP module, or 
wu-imapd.

Users might not like loosing the flags, but sometimes there's no way 
around it.  The only alternative would be moving using sctips, and than 
recreating just the flags using some custom made Perl script as 
background process (imap-sync can't be used reliably for this in general 
case).  There are still problems with this (for example, you transfer an 
message, user marks it as unseen on new server, and than you reflag it 
as seen since that was the way it was on old server - something to keep 
in mind and warn users beforehand).

-- 
Aleksandar Milivojevic <amilivojevic at pbl.ca>    Pollard Banknote Limited
Systems Administrator                           1499 Buffalo Place
Tel: (204) 474-2323 ext 276                     Winnipeg, MB  R3T 1L7
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