mailbox / user migration to a new server

Niels Dettenbach (Syndicat IT & Internet) nd at
Sun Jan 7 03:17:13 EST 2018

Am 6. Januar 2018 23:22:03 MEZ schrieb Scott Lambert 
>With cyrus-imapd on both ends you shouldn't have to know the
>users' passwords.  The cyrus admin user should be able to login
>to the user's mailboxes on both servers.  I believe IMAPsync,
> , has the ability to specify the admin
>login to use when migrating any mailbox.

>I've not used that feature as I'm always migrating from not-cyrus to
>cyrus and keeping the passwords the same. 
>You should just need a CSV file mapping old username to new username
>and a looping shell script calling imapsync for each user.  With that
>much mail, you may want to split the CSV into several chunks and run
>script in parallel with the different files to get more performance.
>The imapsync site has example scripts.

I did this often now and have two simple scripts for such a migration which works even for import from other IMAP servers. it uses simple text files with two columns (old/new box name) with tab or some spaces between - line by line (could easily adapted to other CSV formats). If it help's i can send it tomorrow...

This makes migrations much more easy, as just a common admin user (default cyrus) and his password is required for imapsync.

To get - from a users view - a "one to one" copy with correct dates/timestamps and status a few flags are typically required (i.e. recreate timestamps from headers).

You can speed up the transfer a bit with disabling SSL (if your net topo allows this).

imapsync by default only transfers differences / deltas between source and target mailbox. This makes it easy to i.e. let it run days before to transfer the very most of the content and start it again at user migration to let just clearify the (tylically less) newer modifications of the mailbox tree.

In practice this allows mailbox migrations with near zero downtimes for users.

good luck and
best regards


Niels Dettenbach
Syndicat IT & Internet

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