Courier-IMAP maibox to cyrus-imap maildir

[Aleksandar Milivojevic]

Cristian Mitrana wrote:
>  Courier-imap is only supporting maildirs; take the advice given and 
> use a tool like imapsync or mailutil from uw-imap. For migrating to
> cyrus from another imap server it's the only good option IMHO.
> You risk that pop3 clients will lose sync and have to download again
> messages if they were configured to leave mail on the server.

Tools like imap-sync are cool.  They preserve (almost) all the internal 
information when copying messages.  But, they are cool only if you need 
to convert handfull of mailboxes (or a bit more if they are small).  If 
you have users with huge mailboxes and/or tons of users, they are simply 
too slow.  It takes imap-sync about 30-40 minutes to copy all my IMAP 
folders from one server to another (some of my folders are really huge). 
  I'd estimate that it would take at least day or two if I was to use it 
to move all my users from one server to another (I'm not the only one 
with big mailbox around here).

Not to mention that tools such as imap-sync require administrator to 
know user's passwords (or at least reset them to something administrator 
knows).  This is because they work on IMAP protocol level, and from IMAP 
server perspective, they are simply an IMAP client (no different than 
your mail reader).

In short, for moving individual users around, tools such as imap-sync 
are way to go.  For batch move of multiple users when large amounts of 
mail need to move, you'd need to sacriface some things for speed (namely 
flags such as seen, replied, and so on), and use scripts.

This is discussed in greater detail on the link I provided in my 
previous mailing.  Both solutins are discussed there, with their pros 
and cons, and when to use them.  If you had read it, you wouldn't offer 
imap-sync as the best-fit-for-all-situations solution.

-- 
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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